This is a list of states with nuclear weapons. There are currently eight states that have successfully detonated nuclear weapons. Five are considered to be "nuclear weapons states", an internationally recognized status conferred by the Nuclear Non-Proliferation Treaty (NPT). In order of acquisition of nuclear weapons these are: the United States of America, Russia (successor state to the Soviet Union), the United Kingdom, France and China. Since the formulation of the NPT, three non-signatory states of the NPT have conducted nuclear tests: India, Pakistan, and purportedly North Korea. Additionally, Israel is also strongly suspected to have an arsenal of nuclear weapons though it has refused to confirm or deny this, and there have been reports that over 200 nuclear weapons might be in its inventory. This status is not formally recognized by international bodies as none of these four countries are currently signatories to the Nuclear Non-Proliferation Treaty. Iran has been developing uranium enrichment technology and stands accused by the United States of doing so for weapons purposes. Iran insists that its intentions are limited to domestic nuclear power generation, despite plutonium traces being detected. As of February 4, 2006, the International Atomic Energy Agency referred Iran to the United Nations Security Council in response to concerns on their possible nuclear programs.
Estimated worldwide nuclear stockpiles
The following is a list of nations that have admitted the possession of nuclear weapons, the approximate number of warheads under their control in 2002, and the year they tested their first weapon. This list is informally known in global politics as the "Nuclear Club". With the exception of Russia and the United States (which have subjected their nuclear forces to independent verification under various treaties) these figures are estimates, in some cases quite unreliable estimates. Also, these figures represent total warheads possessed, rather than deployed. In particular, under the SORT treaty thousands of Russian and U.S. nuclear warheads are in inactive stockpiles awaiting processing. The fissile material contained in the warheads can then be recycled for use in nuclear reactors that drive nuclear power plants and some military submarines and warships.
From a high of 65,000 active weapons in 1985, there were about 20,000 active nuclear weapons in the world in 2002. Many of the "decommissioned" weapons were simply stored or partially dismantled, not destroyed.
World map with nuclear weapons development status represented by color. As of October 31, 2006. Red Five "nuclear weapons states" from the NPT Orange Other known nuclear powers Purple States formerly possessing nuclear weapons Yellow States suspected of being in the process of developing nuclear weapons and/or nuclear programs Blue States which at one point had nuclear weapons and/or nuclear weapons research programs Pink States that claim to possess nuclear weapons
*All numbers are estimates from the Natural Resources Defense Council, published in the Bulletin of the Atomic Scientists, unless other references are given. If differences between active and total stockpile are known, they are given as two figures separated by a forward slash. If no specifics are known, only one figure is given. Stockpile number may not contain all intact warheads if a substantial amount of warheads are scheduled for but have not yet gone through dismantlement; not all "active" warheads are deployed at any given time. When a spread of weapons is given (e.g., 0-10), it generally indicates that the estimate is being made on the amount of fissile material which has likely been produced, and the amount of fissile material needed per warhead depends on estimates of a country's proficiency at nuclear weapon design.
Five "nuclear weapons states" from the NPT
The United States of America developed the first atomic weapons during World War II in co-operation with the United Kingdom and Canada, out of the fear that Nazi Germany would develop them first. It tested its first nuclear weapon in 1945 ("Trinity"), and remains the only country to have used nuclear weapons against another nation, during the atomic bombings of Hiroshima and Nagasaki (see: Manhattan Project). It was the first nation to develop the hydrogen bomb, testing it ("Ivy Mike") in 1952 and a deployable version in 1954 ("Castle Bravo"). The USSR tested its first nuclear weapon ("Joe-1") in 1949, in a crash project developed partially with espionage obtained during and after World War II (see: Soviet atomic bomb project). The direct motivation for their weapons development was the development of a balance of power during the Cold War. It tested a primitive hydrogen bomb in 1953 ("Joe-4") and a megaton-range hydrogen bomb in 1955 ("RDS-37"). The Soviet Union also tested the most powerful explosive ever detonated by humans, ("Tsar Bomba"), which had a yield of 100 megatons, but was intentionally reduced to 50. After its dissolution in 1991, its weapons entered officially into the possession of Russia. The United Kingdom tested its first nuclear weapon ("Hurricane") in 1952, drawing largely on data gained while collaborating with the United States during the Manhattan Project. Its program was motivated to have an independent deterrent against the USSR, while also remaining relevant in Cold War Europe. It tested its first hydrogen bomb in 1957. It maintains the Trident fleet of nuclear weapon submarines. France tested its first nuclear weapon in 1960 ("Gerboise Bleue"), based mostly on its own research aided by indirect British help[citations needed] and the experience of French scientists who had worked on the Manhattan Project namely Louis de Broglie, Pierre Auger and Frédéric Joliot. It was motivated by the will of independence vis-à-vis the United States confirmed with France's loosening of ties to NATO, and as an independent deterrent against the USSR. It was also relevant to retain great power status, along side United Kingdom, during the post-colonial Cold War (see: Force de frappe). France tested its first hydrogen bomb in 1968 ("Opération Canopus"). After the Cold War, France has disarmed 175 warheads with the reduction and modernization of its arsenal which has now evolved to a dual system based on submarine-launched ballistic missiles (SSBN) and medium-range air-to-surface missiles (Rafale bombers). However new nuclear weapons are in development and reformed nuclear squadrons were trained during Enduring Freedom operation in Afghanistan. In January 2006, president Jacques Chirac officially stated a terrorist act or the use of massive destruction weapons against France would result in a nuclear counterattack . The Charles de Gaules is currently the last carrier with nuclear weapons deployed by a country. China tested its first nuclear weapon in 1964. China was the first Asian nation to have developed and tested a nuclear weapon. The weapon was developed as a deterrent against both the United States and the USSR. It tested its first hydrogen bomb in 1967 at Lop Nur. The country is currently thought to have had a stockpile of around 130 warheads.
Other known nuclear powers
India has never been a member of the Nuclear Non-Proliferation Treaty. It tested a "peaceful nuclear device", as it was described by the Indian government, in 1974 ("Smiling Buddha"), the first test developed after the creation of the NPT, and created new questions about how civilian nuclear technology could be diverted secretly to weapons purposes (dual-use technology). It appears to have been primarily motivated as a deterrent against China. It tested weaponized nuclear warheads in 1998 ("Operation Shakti"), including a thermonuclear device (though whether the latter was fully successful is a matter of some contention). In July 2005, it was officially recognized by the United States as a "a responsible state with advanced nuclear technology" and agreed to full nuclear cooperation between the two nations. This is seen as a tacit entry into the nuclear club of the above nations. In March 2006, a civil nuclear cooperation deal was signed between President George W Bush and Prime Minister Manmohan Singh. This deal, ratified by United States Congress and United States Senate in December 2006 would pave the path for the United States and other members of the Nuclear Suppliers Group to sell civilian nuclear technology to India. The country is currently thought to have had a stockpile of around 40-50 warheads. Pakistan is not a member of the Nuclear Non-Proliferation Treaty. Pakistan covertly developed nuclear weapons over many decades, beginning in the late 1970s. Pakistan first delved into nuclear power after the establishment of its first nuclear power plant near Karachi with equipment and materials supplied mainly by western nations in the early 1970s. After the detonation of a nuclear bomb by India, the country started its own nuclear weapons development program and established secret, mostly underground, nuclear facilities near the capital Islamabad. It is believed that Pakistan already had nuclear weapons capability by the end of the 1980s. However, this was to remain speculative until 1998 when Pakistan conducted its first nuclear tests at the Chagai Hills, a few days after India conducted its own tests. North Korea was a member of the Nuclear Non-Proliferation Treaty, but announced a withdrawal on January 10, 2003 and did so that April. In February 2005 they claimed to possess functional nuclear weapons, though their lack of a test at the time led many experts to doubt the claim. However, in October 2006, North Korea stated that due to growing intimidation by the USA, it would conduct a nuclear test to confirm its nuclear status. North Korea reported a successful nuclear test on October 9, 2006. Most U.S. intelligence officials believe that North Korea did, in fact, test a nuclear device due to radioactive isotopes detected by U.S. aircraft; however, most agree that the test was probably only partially successful, having less than a kiloton in yield.
Suspected nuclear states
Countries believed to have at least one nuclear weapon, or programs with a realistic chance of producing a nuclear weapon in the near future:
Israel - Israel is not a member of the Nuclear Non-Proliferation Treaty and refuses to officially confirm or deny having a nuclear arsenal, or to having developed nuclear weapons, or even to having a nuclear weapons program. Although Israel claims that the Negev Nuclear Research Center near Dimona is a "research reactor," no scientific reports based on work done there have ever been published. Extensive information about the program in Dimona was also disclosed by technician Mordechai Vanunu in 1986. Imagery analysts can identify weapon bunkers, mobile missile launchers, and launch sites in satellite photographs. It is believed to possess nuclear weapons by the International Atomic Energy Agency, though unlike Iran, has never been referred to the United Nations Security Council. Israel is suspected to have tested a nuclear weapon along with South Africa in 1979, but this has never been confirmed (see Vela Incident). According to the Natural Resources Defense Council and the Federation of American Scientists, Israel possesses around 75-200 weapons.
States suspected of having clandestine nuclear programs
The question of whether individual states without nuclear weapons are trying to develop them is often a controversial one. Accusations of clandestine nuclear programs are often vehemently denied, and may be politically motivated themselves, or simply erroneous. Below are countries who have been accused by a number of governments and intergovernmental agencies as currently attempting to develop nuclear weapons technology who are not suspected as yet having developed it.
Iran - Iran signed the Nuclear Non-Proliferation Treaty and says its interest in nuclear technology, including enrichment, was for civilian purposes only (a right guaranteed under the treaty), but the United States of America's CIA and a few other western countries, mainly the United Kingdom  suspect that this is a cover for a nuclear weapons program, claiming that Iran has little need to develop nuclear power domestically and that it has consistently chosen nuclear options which were dual-use technology rather than those which could only be used for power generation. Former Iranian Foreign Minister Kamal Kharrazi stated on the intentions of his country's nuclear ambitions: "Iran will develop nuclear power abilities and these have to be recognized by the treaties." As of February 4, 2006, the International Atomic Energy Agency referred Iran to the United Nations Security Council in response to Western concerns on their possible nuclear programs. On April 11, 2006, Iran's president announced that the country had successfully enriched uranium to reactor-grade levels for the first time. On April 22, 2006, Iran's envoy to the U.N. nuclear watchdog agency stated the Islamic republic had reached a "basic deal" with the Kremlin to form a joint uranium enrichment venture on Russian territory. Saudi Arabia - In 2003, members of the government stated that due to the worsening relations with the USA, Saudi Arabia was being forced to consider the development of nuclear weapons; however, so far they have denied that they are making any attempt to produce them. It has been rumoured that Pakistan has transferred several nuclear weapons to Saudi Arabia, but this is unconfirmed. In March 2006, the German magazine Cicero reported that Saudi Arabia had since 2003 received assistance from Pakistan to acquire nuclear missiles and warheads. Satellite photos allegedly reveal an underground city and nuclear silos with Ghauri rockets south of the capital Riyadh. Pakistan has denied aiding Saudi Arabia in any nuclear ambitions.
States formerly possessing nuclear weapons
Nuclear weapons have been present in many nations, often as staging grounds under control of other powers. However, in only a few instances have nations given up nuclear weapons after being in control of them; in most cases this has been because of special political circumstances. The fall of the USSR, for example, left several former Soviet-bloc countries in possession of nuclear weapons.
South Africa – South Africa produced six nuclear weapons in the 1980s, but disassembled them in the early 1990s. In 1979 there was a putative detection of a clandestine nuclear test in the Indian Ocean, and it has long been speculated that it was potentially a test by South Africa, perhaps in collaboration with Israel, though this has never been confirmed (see Vela Incident). South Africa signed the Nuclear Non-Proliferation Treaty in 1991.
Former Soviet countries
Belarus – Belarus had 81 single warhead missiles stationed in their territory after the Soviet Union collapsed in 1991. They were all transferred to Russia by 1996. Belarus signed the Nuclear Non-Proliferation Treaty. Kazakhstan – Kazakhstan inherited 1,400 nuclear weapons from the Soviet Union, and transferred them all to Russia by 1995. Kazakhstan has signed the Nuclear Non-Proliferation Treaty. Ukraine - Ukraine has signed the Nuclear Non-Proliferation Treaty. Ukraine inherited about 5,000 nuclear weapons when it became independent from the USSR in 1991, making its nuclear arsenal the third-largest in the world. By 1996, Ukraine had voluntarily disposed of all nuclear weapons within its territory, transferring them to Russia.
States formerly possessing nuclear programs
These are nations known to have initiated serious nuclear weapons programs, with varying degrees of success. All of them are now regarded as currently no longer actively developing, or possessing, nuclear arms. All of the listed countries (or their descendants) signed the Nuclear Non-Proliferation Treaty.
Argentina – Argentina created its National Atomic Energy Commission (CNEA) in 1950 for developing and controlling nuclear energy for peaceful purposes in the country but conducted a nuclear weapon research program under military rule of 1978, at a time when it had signed, but not ratified, the Treaty of Tlatelolco. This program was abandoned after democratization in 1983. However, unofficial reports and U.S. intelligence postulate that Argentina continued some kind of nuclear weapons program during the 1980s (as an attempt to build a nuclear submarine), mainly because of rivalry with Brazil but the program was cancelled. In the early 1990s, Argentina and Brazil established a bilateral inspection agency to verify both countries' pledges to use nuclear energy only for peaceful purposes and on February 10, 1995, Argentina acceded to the Nuclear Non-Proliferation Treaty. Australia – Following World War II, Australian defence policy initiated joint nuclear weapons development with the United Kingdom. Australia provided uranium, land for weapons and rocket tests, and scientific and engineering expertise. Canberra was also heavily involved in the Blue Streak ballistic missile program. In 1955, a contract was signed with a British company to build the Hi-Flux Australian Reactor (HIFAR). HIFAR was considered the first step toward the construction of larger reactors capable of producing substantial volumes of plutonium for nuclear weapons. However, Australia's nuclear ambitions were abandoned by the 1960s, and the country signed the NPT in 1970 (ratified in 1973). Brazil – Military régime conducted a nuclear weapon research program (code-named "Solimões") to acquire nuclear weapons in 1978, in spite of having ratified the Treaty of Tlatelolco in 1968. When an elected government came in to power in 1985, though, the program was ended. On July 13, 1998 President Fernando Henrique Cardoso signed and ratified both the Nuclear Non-Proliferation Treaty (NPT) and the Comprehensive Test Ban Treaty (CTBT), denying that Brazil had developed nuclear weapons. Egypt – Had a nuclear weapon research program from 1954 to 1967. Egypt has signed the Nuclear Non-Proliferation Treaty. Nazi Germany – During World War II, Nazi Germany researched possibilities to develop a nuclear weapon; however, for multiple reasons subject to some controversy, the project was not nearing completion at the end of the war. The research site was sabotaged by British spies and Norwegian partisans, which slowed down their research (see Norwegian heavy water sabotage). Historian Rainer Karlsch, in his 2005 book Hitlers Bombe, has suggested that the Nazis may have tested some sort of "atom bomb" in Thuringia in the last year of the war; it may have been a radiological weapon (rather than a fission weapon), though little reliable evidence of this has surfaced. Some of the German scientists involved also claimed to have sabotaged or falsely reported failures due to personal moral disagreement with Nuclear bomb development (See: German nuclear energy project). Iraq – Iraq has signed the Nuclear Non-Proliferation Treaty. They had a nuclear weapon research program during the 1970s and 1980s. In 1981, Israel destroyed Iraqi nuclear reactor Osiraq. In 1996, the UN's Hans Blix reported that Iraq had dismantled or destroyed all of their nuclear capabilities. In 2003, a multinational coalition headed by the United States invaded Iraq based on intelligence indicating that it possessed weapons prohibited by the UN Security Council. Because of its refusal to fully cooperate with UN inspections, Iraq was strongly suspected by many UNSC members of having some form of nuclear program. However, in 2004 the Duelfer Report concluded Iraq's nuclear program was terminated in 1991. Japan – Japan conducted research into nuclear weapons during World War II though made little headway. (see Japanese atomic program). Japan signed the Nuclear Non-Proliferation Treaty. While Japan has the technological capabilities to develop nuclear weapons in a short time there is no evidence they are doing so. Although Japan's constitution does not forbid it from producing nuclear weapons, the country has been active in promoting non-proliferation treaties. There exists some suspicion that nuclear weapons may be located in US bases in Japan. Japan is also the only nation in the world against whom nuclear weapons have been used in wartime, the cities of Hiroshima and Nagasaki having been destroyed on August 6 and 9, 1945, respectively. Libya – Signed the Nuclear Non-Proliferation Treaty. On December 19, 2003, after the U.S.-led invasion of Iraq and the October 2003 interception of Pakistani-designed centrifuge parts sent from Malaysia (as part of A. Q. Khan's proliferation ring), Libya admitted to possessing a nuclear weapon program and simultaneously announced its intention to end it and dismantle all existing weapons of mass destruction to be verified by unconditional inspections. Poland – Nuclear research began in Poland in the early 1960s, with the first controlled nuclear fission reaction being achieved in the late 1960s. During the 1970s further research resulted in the generation of fusion neutrons through convergent shockwaves. In the 1980s research focused on the development of micro-nuclear reactions, and was under military control. Currently Poland operates the MARIA nuclear research reactor under the control of the Institute of Atomic Energy, in Świerk near Warsaw. Poland has signed the Nuclear Non-Proliferation Treaty and officially possesses no nuclear weapons. Romania – Signed the Nuclear Non-Proliferation Treaty in 1970. In spite of this, under Nicolae Ceauşescu, in the 1980s, Romania had a secret nuclear-weapons development program that was ended after his overthrow in 1989. Now Romania runs a nuclear power plant of two reactor units (with three more under construction) built with Canadian support. It also mines and enriches its own uranium for the plant and has a research program. South Korea began a nuclear weapons program in the early 1970s, which was believed abandoned after signing NPT in 1975. However there have been allegations that program may have been continued after this date by the military government. In late 2004, the South Korean government disclosed to the IAEA that scientists in South Korea had extracted plutonium in 1982 and enriched uranium to near-weapons grade in 2000. Sweden – During the 1950s and 1960s, Sweden seriously investigated nuclear weapons, intended to be deployed over coastal facilities of an invading enemy (the Soviet Union). A very substantial research effort of weapon design and manufacture was conducted resulting in enough knowledge to allow Sweden to manufacture nuclear weapons. A weapon research facility was to be built in Studsvik. Saab made plans for a supersonic nuclear bomber, the A36. However Sweden decided not to pursue a weapon production program and signed the Nuclear Non-Proliferation Treaty. Switzerland – Between 1946 and 1969 Switzerland had a secret nuclear programme that came to light in 1995. By 1963 theoretical basics with detailed technical proposals, specific arsenals, and cost estimates for Swiss nuclear armaments were made. This program was, however, abandoned partly because of financial costs and by signing the NPT on November 27, 1969. The Republic of China (Taiwan) – Conducted a covert nuclear weapon research program from 1964 until 1988 when it was stopped as a result of U.S. pressure. Taiwan signed the Nuclear Non-Proliferation Treaty in 1968. According to a previously classified 1974 U.S. Defense Department memorandum, Secretary of Defense James Schlesinger expressed a view during a meeting with Ambassador Leonard Unger that U.S. nuclear weapons housed in Taiwan needed to be withdrawn.
Socialist Federal Republic of Yugoslavia's nuclear ambitions began as early as 1950s when scientists considered both uranium enrichment and plutonium reprocessing. In 1956, the Vinča fuel reprocessing site was constructed, followed by research reactors in 1958 and 1959, for which the Soviets provided heavy water and enriched uranium. In 1966, plutonium reprocessing tests began in Vinča laboratories, resulting in gram quantities of reprocessed plutonium. During the 1950s and 1960s there was also cooperation in plutonium processing between Yugoslavia and Norway. In 1960 Tito froze the nuclear program for unknown reasons, but restarted it, after India's first nuclear tests, in 1974. The program continued even after Tito's death in 1980, divided into two components – for weapons design and civilian nuclear energy, until a decision to stop all nuclear weapons research was made in July 1987. The civilian nuclear program however resulted in a nuclear power plant Krško built in 1983, now co-owned by Slovenia and Croatia, and used for peaceful production of electricity. Federal Republic of Yugoslavia inherited the Vinča laboratories and 50 kilograms of highly enriched uranium stored at the site. During the NATO bombing of Yugoslavia in 1999, Vinča was never hit because NATO was aware of the HEU. After the end of NATO bombings the U.S. government and the Nuclear Threat Initiative transported the HEU to Russia – the place from which Yugoslavia originally acquired it.
Other nuclear-capable states
Virtually any industrialized nation today has the technical capability to develop nuclear weapons within several years if the decision to do so were made. Nations already possessing substantial nuclear technology and arms industries could do so in no more than a year or two, perhaps even as fast as a few months or weeks, if they so decided to. The larger industrial nations (Japan, Germany, Italy, Australia and Canada for example) could, within several years of deciding to do so, build arsenals rivaling those of the states that already have nuclear weapons. This list below mentions some notable capabilities possessed by certain states that could potentially be turned to the development of nuclear arsenals. This list represents only strong nuclear capability, not the political will to develop weapons. All of the listed countries have signed the Nuclear Non-Proliferation Treaty.
Canada - Canada has a well developed advanced nuclear technology base, large uranium reserves and markets reactors for civilian use. Through extensive power generation and production capabilities, Canada has the technological capabilities to develop nuclear weapons, possessing large amounts of plutonium through power generation. Canada could develop nuclear weapons within a short period of time if attempted. While no nuclear weapons program existed, Canada was technically well placed to proceed with a program as early as 1945 if they wished to do so. Canada has been an important contributor of both expertise and raw materials to the American program in the past, and assisted in the Manhattan Project. In 1959, NATO proposed that the RCAF assume a nuclear strike role in Europe. Thus in 1962 six Canadian CF-104 squadrons based in Europe were formed into the RCAF Nuclear Strike Force armed with B28 nuclear bombs (originally Mk 28) under the NATO nuclear weapons sharing program; the Force was disbanded in 1972 when Canada opted out of the nuclear strike role. Canada accepted having American W-40 nuclear warheads under dual key control on Canadian soil in 1963 to be used on the Canadian BOMARC missiles. The Canadian air force also maintained a stockpile of AIR-2 Genie unguided nuclear air-to-air rockets as the primary wartime weapon on the CF-101 Voodoo all-weather interceptor after 1965. Prime Minister Pierre Trudeau declared Canada would be a nuclear weapon-free country in 1971, and the last American warheads were withdrawn in 1984. Canada gave India its first research reactor, the CIRUS, in 1956 and this reactor was used to make the nuclear material used in India's first nuclear device. Canada also produces the renowned CANDU reactor and has sold the technology to several countries, including China, South Korea, India, Romania, Argentina, and Pakistan. However, there is no credible evidence that CANDU reactors were used to breed weapons grade material for either India or Pakistan. Canada nevertheless cut off nuclear trade with those two countries after they detonated nuclear weapons. Germany - While Germany is a signatory of the NPT, it has the means to equip itself rapidly with nuclear weapons. It has an advanced nuclear industry capable of manufacturing reactors, enriching uranium, fuel fabrication, and fuel reprocessing and it operates 19 power reactors producing one third of its total electrical needs. On the other hand, Germany has since 1945 made no serious attempts of acquiring or developing its own strategic delivery systems. Considerable numbers of nuclear weapons have been stationed both in East and West Germany during the Cold War, starting as early as 1955. Under the nuclear sharing scheme, West German soldiers would in theory have been authorized to use nuclear weapons provided by the US in event of a massive Warsaw Pact attack. Several dozen such weapons reputedly remain on bases in western Germany. Since 1998, Germany has adopted a policy of eliminating nuclear power, although slow progress had been made. On January 26, 2006, the former defence minister, Rupert Scholz, said that Germany may need to build its own nuclear weapons to counter terrorist threats. The Treaty on the Final Settlement with Respect to Germany also specified that Germany wouldn't acquire nuclear weapons. Japan - Japan makes extensive use of nuclear energy in nuclear reactors, generating a significant percentage of the electricity in Japan. Japan has the third largest nuclear energy production after the U.S. and France, and plans to produce over 40% of its electricity using nuclear power by 2010. Significant amounts of plutonium are created as a by-product of the energy production, and Japan had 4.7 tons of plutonium in December 1995. Japan also has its own centrifuge-based uranium enrichment program, which could also be used to create highly enriched uranium suitable for bombs. Experts believe Japan has the technology, raw materials, and the capital to produce nuclear weapons within one year if necessary, and some analysts consider it a "de facto" nuclear state for this reason. Japan has been quietly reconsidering its nuclear status because of the ongoing crisis over North Korean nuclear weapons. Italy - Italy has operated a number of nuclear reactors, both for power and for research. The country was also a base for the Jupiter missile in the 1960s and later the GLCM nuclear-armed ground-launched variant of the Tomahawk cruise missile during the 1980s, despite strong public outcry. Several warheads are still in the NATO arsenal in Italy, mostly in form of airplane bombs. While no evidence suggests that Italy intends to develop or deploy nuclear weapons, such a capability exists - estimates from as far back as the mid-80s show that Italy could begin and complete a nuclear weapons program in as little as one year. Lithuania - Nuclear power reactors produce 77% of Lithuania's electricity and it has 2 of the world's most powerful reactors in its territory. However, one of these reactors was recently shut down. Lithuania has the means of legally acquiring fissile materials for power plants. Lithuania also has former launch sites for Soviet Union missiles. However, there is no political will to develop nuclear weapons in Lithuania. The Netherlands - Operates a power reactor at Borsele, producing 452 MW, which satisfies 5% of its electrical needs and has an advanced nuclear research and medical isotopes facility at Petten. Several Dutch companies are key participants in the tri-national Urenco uranium enrichment consortium. By 2000 the Netherlands had about 2 tons of separated reactor grade plutonium. Even though the capability exists, there is no evidence for nuclear weapon production in the Netherlands. Also, in the light of the fierce opposition against nuclear weapon deployment in the 1980s, it is highly unlikely that such a programme will ever exist. Norway - Has since the 1950s operated two scientific reactors at Kjeller and Halden, and there are currently no known plans for constructing new reactors. According to environmental organization Bellona, Norway exported equipment and technology for plutonium enrichment and heavy water for use in reactors to India and Israel during the 1960s, contributing to their nuclear ambitions. It is estimated Norway could complete a nuclear weapons program in a year with adequate funding, but public opposition to nuclear weapons is considerable.
The history of nuclear weapons chronicles the development of nuclear weapons—devices of enormous destructive potential which derive their energy from nuclear fission or nuclear fusion reactions—starting with the scientific breakthroughs of the 1930s which made their development possible, continuing through the nuclear arms race and nuclear testing of the Cold War, and finally with the questions of proliferation and possible use for terrorism in the early 21st century.
The first fission weapons ("atomic bombs") were developed in the United States during World War II in what was called the Manhattan Project, at which point two were dropped on Japan. The Soviet Union started development shortly thereafter with their own atomic bomb project, and not long after that both countries developed even more powerful fusion weapons ("hydrogen bombs"). During the Cold War, these two countries each acquired nuclear weapons arsenals numbering in the thousands, placing many of them onto rockets which could hit targets anywhere in the world. Currently there are at least eight countries with functional nuclear weapons. A considerable amount of international negotiating has focused on the threat of nuclear warfare and the proliferation of nuclear weapons to new nations or groups.
There have been (at least) four major false alarms, the most recent in 1995, that almost resulted in the US or Russia launching its weapons in retaliation for a supposed attack.
In the first decades of the twentieth century, physics was revolutionized with developments in the understanding of the nature of atoms. In 1898, Pierre Curie and his wife Marie had discovered that present in pitchblende, an ore of uranium, was a substance which emitted large amounts of radioactivity, which they named radium. This raised the hopes of both scientists and lay people that the elements around us could contain tremendous amounts of unseen energy, waiting to be tapped.
Experiments by Ernest Rutherford in 1911 indicated that the vast majority of an atom's mass was contained in a very small nucleus at its core, made up of protons, surrounded by a web of whirring electrons. In 1932, James Chadwick discovered that the nucleus contained another fundamental particle, the neutron, and in the same year John Cockcroft and Ernest Walton "split the atom" for the first time, the first occasion on which an atomic nucleus of one element had been successfully changed to a different nucleus by artificial means.
Great changes were also mounting on the political scene. Adolf Hitler was appointed chancellor of Germany in January 1933 and, within only three months, had asserted dictatorial control over the country. As part of the anti-Semitic ideology of Nazism, all Jewish civil servants were fired from their posts, including university professors, many of whom fled to Britain and the United States, if they could find jobs.
In 1934, French physicists Irène and Frédéric Joliot-Curie discovered that artificial radioactivity could be induced in stable elements by bombarding them with alpha particles, and in the same year Italian physicist Enrico Fermi reported similar results when bombarding uranium with neutrons.
In 1938, Germans Otto Hahn and Fritz Strassmann released the results of their finding proving that what Fermi had witnessed in 1934 was no less than the bursting of the uranium nucleus: nuclear fission. Immediately afterwards, Lise Meitner and Otto Robert Frisch described the theoretical mechanisms of fission and revealed that large amounts of binding energy were released in the process. Hungarian Leó Szilárd confirmed with his own experiments that along with energy, neutrons were given off in the reaction as well, creating the possibility of a nuclear chain reaction, whereby each fission created two or more other fissions, exponentially releasing energy.
As the Nazi army marched into first Czechoslovakia in 1938, and then Poland in 1939, officially beginning World War II, many of Europe's top physicists had already begun to flee from the imminent conflict. Scientists on both sides of the conflict were well aware of the possibility of utilizing nuclear fission as a weapon, but at the time no one was quite sure how it could be done. In the early years of the Second World War, physicists abruptly stopped publishing on the topic of fission, an act of self-censorship to keep the opposing side from gaining any advantages.
In nuclear fission, the nucleus of a fissile atom (in this case, enriched uranium) absorbs a thermal neutron, becomes unstable, and splits into two new atoms, releasing some energy and between one and three new neutrons, which can perpetuate the process.
From Los Alamos to Hiroshima
By the beginning of World War II, there was concern among scientists in the Allied nations that Nazi Germany might have their own project to develop fission-based weapons. Organized research first began in Britain as part of the "TUBE ALLOYS" project, and in the United States a small amount of funding was given for research into uranium weapons starting in 1939 with the Uranium Committee under Lyman James Briggs. At the urging of British scientists, though, who had made crucial calculations indicating that a fission weapon could be completed within only a few years, by 1941 the project had been wrested into better bureaucratic hands, and in 1942 came under the auspices of General Leslie Groves as the Manhattan Project. Scientifically led by the American physicist Robert Oppenheimer, the project brought together the top scientific minds of the day (many exiles from Europe) with the production power of American industry for the goal of producing fission-based explosive devices before Germany could. Britain and the U.S. agreed to pool their resources and information for the project, but the other Allied power—the Soviet Union under Joseph Stalin—was not informed.
A massive industrial and scientific undertaking, the Manhattan Project involved many of the world's great physicists in the scientific and development aspects. The United States made an unprecedented investment into wartime research for the project, which was spread across over 30 sites in the U.S. and Canada. Scientific knowledge was centralized at a secret laboratory known as Los Alamos, previously a small ranch school near Santa Fe, New Mexico.
Uranium appears in nature primarily in two isotopes: uranium-238 and uranium-235. When the nucleus of uranium-235 absorbs a neutron, it undergoes nuclear fission, splitting into two "fission products" and releasing energy and 2.5 neutrons on average. Uranium-238, on the other hand, absorbs neutrons and does not fission, effectively putting a stop to any ongoing fission reaction. It was discovered that an atomic bomb based on uranium would need to be made of almost completely pure uranium-235 (at least 80% pure), or else the presence of uranium-238 would quickly curtail the nuclear chain reaction. The team of scientists working on the Manhattan Project immediately realized that one of the largest problems they would have to solve was how to remove uranium-235 from natural uranium, which was composed of 99.3% uranium-238. Two methods were developed during the wartime project, both of which took advantage of the fact that uranium-238 has a slightly greater atomic mass than uranium-235: electromagnetic separation and gaseous diffusion—methods which separated isotopes based on their differing weights. Another secret site was erected at rural Oak Ridge, Tennessee, for the large-scale production and purification of the rare isotope. It was a massive investment: at the time, one of the Oak Ridge facilities (K-25) was the largest factory under one roof. The Oak Ridge site employed tens of thousands of employees at its peak, most of whom had no idea what they were working on.
Berkeley physicist Robert Oppenheimer led the Allied scientific effort at Los Alamos.
Though uranium-238 cannot be used inside an atomic bomb, when it absorbs a neutron it transforms first into an unstable element, uranium-239, and then decays into neptunium-239 and finally the relatively stable plutonium-239, an element which does not exist in nature. Plutonium is also fissile and can be used to create a fission reaction, and after Enrico Fermi achieved the world's first sustained and controlled nuclear chain reaction in the creation of the first "atomic pile"—a primitive nuclear reactor—in a basement at the University of Chicago, massive reactors were secretly created at what is now known as Hanford Site in the state of Washington, using the Columbia River as cooling water, to transform uranium-238 into plutonium for a bomb.
For a fission weapon to operate, there must be a critical mass—the amount needed for a self-sustaining nuclear chain reaction—of fissile material bombarded with neutrons at any one time. The simplest form of nuclear weapon would be a gun-type fission weapon, where a sub-critical mass of fissile material (such as uranium-235) would be shot at another sub-critical mass of fissile material. The result would be a super-critical mass which, when bombarded with neutrons, would undergo fission at a rapid rate and create the desired explosion.
But it was soon discovered that plutonium cannot be used in a "gun assembly," as it has too high a level of background neutron radiation; it undergoes spontaneous fission to a very small extent. If plutonium were used in a "gun assembly," the chain reaction would start in the split seconds before the critical mass was assembled, blowing the weapon apart before it would have any great effect (this is known as a fizzle). After some despair, Los Alamos scientists discovered another approach: using chemical explosives to implode a sub-critical sphere of plutonium, which would increase its density and make it into a critical mass. The difficulties with implosion were in the problem of making the chemical explosives deliver a perfectly uniform shock wave upon the plutonium sphere—if it were even slightly asymmetric, the weapon would fizzle (which would be expensive, messy, and not a very effective military device). This problem was circumvented by the use of hydrodynamic "lenses"—explosive materials of differing densities—which would focus the blast waves inside the imploding sphere, akin to the way in which an optical lens focuses light rays.
After D-Day, General Groves had ordered a team of scientists—Project Alsos—to follow eastward-moving victorious Allied troops into Europe in order to assess the status of the German nuclear program (and to prevent the westward-moving Russians from gaining any materials or scientific manpower). It was concluded that while Nazi Germany had also had an atomic bomb program, headed by Werner Heisenberg, the government had not made a significant investment in the project, and had been nowhere near success.
By the unconditional surrender of Germany on May 8, 1945, the Manhattan Project was still months away from a working weapon. That April, after the death of American President Franklin D. Roosevelt, former Vice-President Harry S. Truman was told about the secret wartime project for the first time.
Because of the difficulties in making a working plutonium bomb, it was decided that there should be a test of the weapon, and Truman wanted to know for sure if it would work before his meeting with Joseph Stalin at an upcoming conference on the future of postwar Europe. On July 16, 1945, in the desert north of Alamogordo, New Mexico, the first nuclear test took place, code-named "Trinity," using a device nicknamed "the Gadget." The test released the equivalent of 19 kilotons of TNT, far mightier than any weapon ever used before. The news of the test's success was rushed to Truman, who used it as leverage at the upcoming Potsdam Conference, held near Berlin.
After hearing arguments from scientists and military officers over the possible uses of the weapons against Japan (though some recommended using them as "demonstrations" in unpopulated areas, most recommended using them against "built up" targets, a euphemistic term for populated cities), Truman ordered the use of the weapons on Japanese cities, hoping it would send a strong message which would end in the capitulation of the Japanese leadership and avoid a lengthy invasion of the island. On August 6, 1945, a uranium-based weapon, "Little Boy", was let loose on the Japanese city of Hiroshima. Three days later, a plutonium-based weapon, "Fat Man", was dropped onto the city of Nagasaki. The atomic bombs killed at least one hundred thousand Japanese outright, most of them civilians, with the heat, radiation, and blast effects. Many tens of thousands would die later of radiation sickness and related cancers. Truman promised a "rain of ruin" if Japan did not surrender immediately, threatening to eliminate Japanese cities, one by one; Japan surrendered on August 15. Truman's threat was in fact a bluff, since the US had not completed more atomic bombs at the time.
The weapons had been developed, and their power had been demonstrated to the world. The United States held a monopoly on nuclear weapons, but nobody thought this could last forever—the principles were based in fundamental research, which could be duplicated almost anywhere. The atomic age had begun.
Soviet atomic bomb project
The Soviet Union was not invited to share in the new weapons developed by the United States and the other Allies, but they were not to be left out of the nuclear club for long. All during the war, information had been pouring in from a number of volunteer spies involved with the Manhattan Project (known in Soviet cables under the code-name of Enormoz), and the Soviet nuclear physicist Igor Kurchatov was carefully watching the Allied weapons development. As such, it came as no surprise to Stalin when Truman had informed him at the Potsdam conference that he had a "powerful new weapon." Truman was shocked at Stalin's lack of interest.
The Soviet spies in the U.S. project were all volunteers and none were Russians. One of the most valuable, Klaus Fuchs, was a German émigré theoretical physicist who had been a part in the early British nuclear efforts and had been part of the UK mission to Los Alamos during the war. Fuchs had been intimately involved in the development of the implosion weapon, and passed on detailed cross-sections of the "Trinity" device to his Soviet contacts. Other Los Alamos spies—none of whom knew each other—included Theodore Hall and David Greenglass. The information was kept but not acted upon, as Russia was still too busy fighting the war in Europe to devote resources to this new project.
In the years immediately after World War II, the issue of who should control atomic weapons became a major international point of contention. Many of the Los Alamos scientists who had built the bomb began to call for "international control of atomic energy", often calling for either control by transnational organizations or the purposeful distribution of weapons information to all superpowers, but due to a deep distrust of the intentions of the Soviet Union, both in postwar Europe and in general, the policy-makers of the United States worked to attempt to secure an American nuclear monopoly. A half-hearted plan for international control was proposed at the newly formed United Nations by Bernard Baruch ("The Baruch Plan"), but it was clear both to American commentators—and to the Soviets—that it was an attempt primarily to stymie Russian nuclear efforts. The Soviets vetoed the plan, effectively ending any immediate postwar negotiations on atomic energy, and made overtures towards banning the use of atomic weapons in general.
Soviet physicist Igor Kurchatov was in charge of analyzing the espionage coming in about the American nuclear project.
All the while, the Soviets had put their full industrial and manpower might into the development of their own atomic weapons. The initial problem for the Soviets was primarily one of resources—they had not scouted out uranium resources in the Soviet Union and the U.S. had made deals to seize monopolies over the largest known reserves in the Belgian Congo. The USSR used penal labour to mine the old deposits in Czechoslovakia—now an area under their control—and searched for other domestic deposits (which were eventually found).
Two days after the bombing of Nagasaki, the U.S. government released an official technical history of the Manhattan Project, authored by Princeton physicist Henry DeWolf Smyth, known colloquially as the Smyth Report. The sanitized summary of the wartime effort focused primarily on the production facilities and scale of investment, written in part to justify the wartime expenditure to the American public. The Soviet program, under the suspicious watch of former NKVD chief Lavrenty Beria (a participant and victor in Stalin's Great Purge of the 1930s), would use the Report as a blueprint, seeking to duplicate as much as possible the American effort. The "secret cities" used for the Soviet equivalents of Hanford and Oak Ridge literally vanished from the maps for decades to come.
At the Soviet equivalent of Los Alamos, Arzamas-16, physicist Yuli Khariton led the scientific effort to develop the weapon. Beria distrusted his scientists, however, and he distrusted the carefully collected espionage information. As such, Beria assigned multiple teams of scientists to the same task without informing each team of the other's existence. If they arrived at different conclusions, Beria would bring them together for the first time and have them debate with their newfound counterparts. Beria used the espionage information as a way to double-check the progress of his scientists, and in his effort for duplication of the American project even rejected more efficient bomb designs in favor of ones which more closely mimicked the tried-and-true "Fat Man" bomb used by the U.S. against Nagasaki.
The iron hand of NKVD chief Lavrenty Beria was put in charge of the Russian project.
After World War II, the balance of power between the Eastern and Western blocs, resulting in the fear of global destruction, prevented the further military use of atomic bombs. This fear was even a central part of Cold War strategy, referred to as the doctrine of Mutually Assured Destruction ("MAD" for short). So important was this balance to international political stability that a treaty, the Anti-Ballistic Missile Treaty (or ABM treaty), was signed by the U.S. and the USSR in 1972 to curtail the development of defenses against nuclear weapons and the ballistic missiles which carry them. This doctrine resulted in a large increase in the number of nuclear weapons, as each side sought to ensure it possessed the firepower to destroy the opposition in all possible scenarios and against all perceived threats.
Early delivery systems for nuclear devices were primarily bombers like the United States B-29 Superfortress and Convair B-36, and later the B-52 Stratofortress. Ballistic missile systems, based on Wernher von Braun's World War II designs (specifically the V2 rocket), were developed by both United States and Soviet Union teams (in the case of the U.S., effort was directed by the German scientists and engineers). These systems, after testing, were used to launch satellites, such as Sputnik, and to propel the Space Race, but they were primarily developed to create the capability of Intercontinental Ballistic Missiles (ICBMs) with which nuclear powers could deliver that destructive force anywhere on the globe. These systems continued to be developed throughout the Cold War, although plans and treaties, beginning with the Strategic Arms Limitation Treaty (SALT I), restricted deployment of these systems until, after the fall of the Soviet Union, system development essentially halted, and many weapons were disabled and destroyed (see nuclear disarmament).
Relative sizes of a number of nuclear weapons.
There have been a number of potential nuclear disasters. Following air accidents U.S. nuclear weapons have been lost near Atlantic City, New Jersey (1957); Savannah, Georgia (1958) (see Tybee Bomb); Goldsboro, North Carolina (1961); off the coast of Okinawa (1965); in the sea near Palomares, Spain (1966); and near Thule, Greenland (1968). Most of the lost weapons were recovered, the Spanish device after three months' effort by the DSV Alvin and DSV Aluminaut. The Soviet Union was less forthcoming about such incidents, but the environmental group Greenpeace believes that there are around forty non-U.S. nuclear devices that have been lost and not recovered, compared to eleven lost by America, mostly in submarine disasters. The U.S. has tried to recover Soviet devices, notably in the 1974 Operation Jennifer using the specialist salvage vessel Hughes Glomar Explorer.
On January 27, 1967, more than 60 nations signed the Outer Space Treaty, banning nuclear weapons in space.
The end of the Cold War failed to end the threat of nuclear weapon use, although global fears of nuclear war reduced substantially.
In a major move of de-escalation, Boris Yeltsin, on January 26, 1992, announced that Russia planned to stop targeting United States cities with nuclear weapons.
The nuclear arms race was a competition for supremacy in nuclear weapons between the United States and Soviet Union during the Cold War. During the Cold War, in addition to the American and Soviet nuclear stockpiles, other countries also developed nuclear weapons as well, though none engaged in warhead production on the same size as the two superpowers. An additional nuclear arms race developed between India and Pakistan during the end of the 1990s.
U.S. and USSR/Russian nuclear weapons stockpiles, 1945-2006.
World War II
The first nuclear weapon was created by the American Manhattan Project during the Second World War and was developed for use against the Axis powers. Scientists in the Soviet Union, then an ally of the United States, were aware of the possibility of nuclear weapons and had been doing some work in that direction. Soviet scientists first became aware the Americans were almost certainly working on atomic weapons when all related articles disappeared from physics journals.
The Soviet Union, despite being an ally, was not informed of the American experiments until the Potsdam Conference in 1945. The Americans did not trust the Soviets to keep the information from German spies; there was also deep distrust of the Soviets and their intentions, despite the wartime partnership. Even during the war many government and military figures in the USA saw the USSR as a potential enemy in the future.
The Soviets were well aware of the program due to a spy ring operating within the American nuclear program. The atomic spies (including Klaus Fuchs  and Theodore Hall) kept Stalin well informed of American developments . When U.S. Vice President Harry S. Truman informed Stalin of the weapons, he was surprised at how calmly Stalin took the news and thought that Stalin had not understood what he had told him. In fact Stalin had long been aware of the program. The American program had been so secret that even Truman did not know about the weapons until he became president; Stalin had thus known about the Manhattan Project before Truman himself did.
In August of 1945 Truman ordered two bombs dropped on the Japanese cities of Hiroshima and Nagasaki, by the B-29 bombers Enola Gay and Bock's Car respectively, ostensibly to quickly end the war though questions have remained about additional motivations as well (see Atomic bombings of Hiroshima and Nagasaki).
Early Cold War
The years immediately after the Second World War the Americans had a nuclear monopoly, on both specific knowledge and, most importantly, raw materials. Initially it was thought that uranium was relatively rare in the world , but this was discovered to be incorrect . While American leaders hoped the monopoly would be able to win concessions out of the Soviet Union, this proved ineffective. Stalin knew that he was at a disadvantage; However, he felt that the only solution was to bluff that he was certain the Americans would not use the weapons, and wouldn't care much if they did. Stalin guessed correctly that the American policy makers would not risk another massive war over the relatively removed issues like Berlin or Czechoslovakia, and additionally many felt compelled to give the Soviets concessions for their massive sacrifices in their front against Germany.
Behind the scenes the Soviet regime was working furiously to build their own atomic weapons . During the war Soviet efforts had been limited by a lack of uranium, but new supplies in Eastern Europe were taken and provided a steady supply while the Soviets developed a domestic source. Physicists were given massive funding and treated like royalty, but were also threatened with being shot if they did not make significant progress. The much feared NKVD head Lavrenty Beria was put in charge of the development process. The Soviet effort was aided by the information provided by their spies in the United States, however the information was not freely given to scientists and was instead used as an additional "check" on their progress (Beria trusted neither the scientists nor the espionage). While American thinkers had predicted that the USSR would not have nuclear weapons until the mid-1950s, the first Soviet bomb was detonated on August 29, 1949 , shocking the entire world. The weapon (called "Joe One" by the West) was more or less a copy of the weapon which the United States had dropped on Japan ("Fat Man").
Both governments devoted massive amounts of resources to increasing the quality and quantity of their nuclear arsenal. Both nations quickly began work on hydrogen bombs and the United States detonated the first such device on November 1, 1952 . Again the Soviets surprised the Americans by exploding a deployable thermonuclear device of their own the next August, though it was not actually a "true" multi-stage hydrogen bomb (that would wait until 1954) . The Soviet H-bomb was almost completely a product of domestic research, as their espionage sources in the USA had only worked on very preliminary (and incorrect) versions of the hydrogen bomb.
Delivery methods, such as the bomber fleets, were also expanded. The United States began with a considerable lead in this area, but the widespread introduction of jet powered interceptor aircraft upset this balance somewhat by reducing the effectiveness of the US bomber fleet. In 1949 Curtis LeMay was placed in command of the Strategic Air Command and started a program to update the bomber fleet to one that was all-jet. During the early 1950s the B-47 and B-52 were introduced, giving the US the ability to convincingly penetrate the USSR.
The most important development in terms of delivery in the 1950s was the introduction of ICBMs. Missiles had long been seen as the ideal platform for nuclear weapons and in 1957 on the 4th of October with the launch of Sputnik the Soviet Union showed the world that they had missiles that could hit anywhere in the world. The United States launched their own on the 31 October 1959.
The period also saw attempts begin to defend against nuclear weapons. Both powers built large radar arrays to detect incoming bombers and missiles. Fighters to use against bombers and anti-ballistic missiles to use against ICBMs were also developed. Large underground bunkers were constructed to save the leadership of the superpowers, and individuals were told to build fallout shelters and taught how to react to a nuclear attack (civil defense).
Mutually Assured Destruction (MAD)
All of these defensive measures were far from foolproof and by the 1950s both the United States and Soviet Union had the power to obliterate the other side. Both sides developed a "second-strike" capability , i.e. they could launch a devastating attack even after sustaining a full assault from the other side (especially by means of submarines). This policy was part of what became known as Mutually Assured Destruction: both sides knew that any attack upon the other would be suicide for themselves as well, and thus would (in theory) restrain from attacking one another.
Both Soviet and American thinkers hoped to use nuclear weapons to extract concessions from the other side, or from other powers such as China, but the risk of any use of these weapons were so large that both sides refrained from what John Foster Dulles referred to as brinkmanship. While some like General Douglas MacArthur argued nuclear weapons should be used during the Korean War both Truman and Eisenhower disagreed.
Both sides were also unaware of how their relative arsenals compared. The Americans tended to be lacking in confidence, earlier in the 1950s they believed in a non-existent "bomber gap" (aerial photography later discovered that the Soviets had been playing a sort of Potemkin village game with their bombers in their military parades, flying them in large circles to make it appear they had far more than they truly did), and the 1960 American presidential election saw accusations of a wholly spurious "missile gap" between the Soviets and the Americans. The Soviet government structure tended to exaggerate the power of Soviet weapons to the leadership and Nikita Khrushchev.
An additional controversy formed in the United States during the early-1960s over whether or not it was known if their weapons would work at all if it came down to it. All of the individual components of nuclear missiles had been tested separately (warheads, navigation systems, rockets), but it had been infeasible to test them all as a whole. Critics charged that it was not really known how a warhead would function in the gravity forces and temperature differences encountered in the upper atmosphere and outer space, and Kennedy was unwilling to run a risky test of an ICBM with a live warhead. The closest thing to an actual test, Operation Frigate Bird, which involved testing a live submarine launching a ballistic missile, was challenged by critics (including Curtis LeMay, who used doubt over missile accuracy to encourage the development of new bombers) on the grounds that it was a single test (and could therefore be an anomaly), was a lower-altitude SLBM (and therefore was subject to different conditions than an ICBM), and that significant modifications had been made to its warhead before testing (as that particular warhead was known to be potentially prone to predetonation).
Initial nuclear proliferation
In addition to the United States and the Soviet Union, three other nations, the United Kingdom , People's Republic of China , and France  also developed far smaller nuclear stockpiles. In 1952, the United Kingdom became the third nation to possess nuclear weapons when it detonated an atomic bomb in Operation Hurricane on October 3, 1952. During the Cold War, British nuclear deterrence revolved around the Resolution class ballistic missile submarines armed with the American-built Polaris missile and the WE.177 gravity bomb.
France became the fourth nation to possess nuclear weapons on February 13, 1960, when the atomic bomb Gerboise Bleue was detonated in Algeria, then still a French colony. During the Cold War, the French nuclear deterrent was centered around the Force de frappe, a nuclear triad consisting of Dassault Mirage IV bombers carrying such nuclear weapons as the AN-22 gravity bomb and the ASMP stand-off attack missile, Pluton and Hades ballistic missiles, and the Redoutable class submarine armed with strategic nuclear missiles.
The People's Republic of China became the fifth nuclear power on October 16, 1964, when it detonated a uranium-235 bomb in a test codenamed 596. Due to Soviet/Chinese tensions, the Chinese may have used nuclear weapons against either the United States or the Soviet Union in the event of a US/USSR nuclear war. During the Cold War, the Chinese nuclear deterrent consisting of gravity bombs carried aboard H-6 bomber aircraft and within missile systems.
Economic problems caused by the arms race in both powers, combined with China's new role and the ability to verify disarmament led to a number of arms control agreements beginning in the 1970s. This period known as Détente allowed both states to reduce their spending on weapons systems. SALT I and SALT II and all limited the size of the states arsenals. Bans on nuclear testing, anti-ballistic missile systems, and weapons in space all attempted to limit the expansion of the arms race though the Partial Test Ban Treaty.
These treaties were only partially successful. Both states continued building massive numbers of nuclear weapons, and new technologies such as MIRVs limited the effectiveness of the treaties. Both superpowers retained the ability to destroy each other many times over.
Reagan and Star Wars
Towards the end of Jimmy Carter's presidency, and continued strongly through the subsequent presidency of Ronald Reagan, the United States rejected disarmament and tried to restart the arms race through the production of new weapons and anti-weapons systems. The central part of this strategy was the Strategic Defense Initiative , a space based anti-ballistic missile system derided as "Star Wars" by its critics. During the second part of 1980's, the Soviet economy was teetering towards collapse and was unable to match American arms spending. Numerous negotiations by Mikhail Gorbachev attempted to come to agreements on reducing nuclear stockpiles, but the most radical were rejected by Reagan as they would also prohibit his SDI program.
With the end of the Cold War the United States, and especially Russia, cut down on nuclear weapons spending. Fewer new systems were developed and both arsenals have shrunk. But both states still maintain stocks of nuclear missiles numbering in the thousands. In the USA, stockpile stewardship programs have taken over the role of maintaining the aging arsenal.
After the Cold War ended, a large amount of resources and money which was once spent on developing nuclear weapons was then spent on repairing the environmental damage produced by the nuclear arms race, and almost all former production sites are now major cleanup sites. In the USA, the plutonium production facility at Hanford, Washington and the uranium molding facility at Rocky Flats, Colorado are among the most polluted sites.
United States policy and strategy regarding nuclear proliferation was outlined in 1995 in the document "Essentials of Post-Cold War Deterrence".
India and Pakistan
The South-Asian states of India and Pakistan have also engaged in a nuclear arms race. India detonated what it called a "peaceful nuclear device" in 1974 ("Smiling Buddha")  in response primarily to the development of a weapon by its neighbor China a decade before. In the last few decades of the 20th century, however, both Pakistan and India began to develop nuclear-capable rockets, and Pakistan had its own covert bomb program which extended over many years since the first Indian weapon was detonated. In 1998, both India and Pakistan tested their nuclear weapons in a tit-for-tat fashion (Operation Shakti for India), with India claiming to have tested a hydrogen bomb as well (though the validity of this is disputed). Their arms race is somewhat analogous to the US/USSR race, except that both the amount of resources which each can devote to weapons and the distances to be traversed are far less.
Milestone nuclear explosions
The following list is of milestone nuclear explosions. In addition to the atomic bombings of Hiroshima and Nagasaki, the first nuclear test of a given weapon type for a country is included, and tests which were otherwise notable (such as the largest test ever). All yields (explosive power) are given in their estimated energy equivalents in kilotons of TNT (see megaton).
"Deployable" refers to whether the device tested could be hypothetically used in actual combat (in contrast with a proof-of-concept device). "Staging" refers to whether it was a "true" hydrogen bomb of the so-called Teller-Ulam configuration or simply a form of a boosted fission weapon. For a more complete list of nuclear test series, see List of nuclear tests. Some exact yield estimates, such as that of the Tsar Bomba and the tests by India and Pakistan in 1998, are somewhat contested among specialists.
A nuclear explosion occurs as a result of the rapid release of energy from an uncontrolled nuclear reaction. The driving reaction may be nuclear fission, nuclear fusion or a multistage cascading combination of the two.
Atmospheric nuclear explosions are associated with "mushroom clouds" although mushroom clouds can occur with large chemical explosions and it is possible to have an air burst nuclear explosion without these clouds. Atmospheric nuclear explosions produce large amounts of radiation and radioactive debris. In 1963, all nuclear and many non-nuclear states signed the Limited Test Ban Treaty, pledging to refrain from testing nuclear weapons in the atmosphere, underwater, or in outer space. The treaty permitted underground tests.
The primary application to date has been military (i.e. nuclear weapons). However, there are other potential applications, which have not yet been explored, or have been considered all but abandoned. They include:
A nuclear explosion (nuclear detonation) has occurred on Earth twice using a nuclear weapon during war (during World War II, the atomic bombings of Hiroshima and Nagasaki), about 2,000 times during testing of nuclear weapons, and about 27 times in the U.S. and 156 in the U.S.S.R. in a series of peaceful nuclear explosions; see Operation Plowshare; and Nuclear Explosions for the National Economy
Milestone nuclear explosions
The following list is of milestone nuclear explosions. In addition to the atomic bombings of Hiroshima and Nagasaki, the first nuclear test of a given weapon type for a country is included, and tests which were otherwise notable (such as the largest test ever). All yields (explosive power) are given in their estimated energy equivalents in kilotons of TNT (see megaton).
"Deployable" refers to whether the device tested could be hypothetically used in actual combat (in contrast with a proof-of-concept device). "Staging" refers to whether it was a "true" hydrogen bomb of the so-called Teller-Ulam configuration or simply a form of a boosted fission weapon. For a more complete list of nuclear test series, see List of nuclear tests. Some exact yield estimates, such as that of the Tsar Bomba and the tests by India and Pakistan in 1998, are somewhat contested among specialists.
Effects of a nuclear explosion
The energy released from a nuclear weapon comes in four primary categories:
* Blast—40-60% of total energy * Thermal radiation—30-50% of total energy * Ionizing radiation—5% of total energy * Residual radiation—5-10% of total energy
An American nuclear test.
However, the above values vary depending on the design of the weapon, and the environment in which it is detonated. The interaction of the X-rays and debris with the surroundings determines how much energy is produced as blast and how much as light. In general, the denser the medium around the bomb, the more it will absorb, and the more powerful the shockwave will be. Thermal radiation drops off the slowest with distance, so the larger the weapon the more important this effect becomes. Ionizing radiation is strongly absorbed by air, so it is only dangerous by itself for smaller weapons. Blast damage falls off more quickly than thermal radiation but more slowly than ionizing radiation.
The dominant effects of a nuclear weapon (the blast and thermal radiation) are the same physical damage mechanisms as conventional explosives, but the energy produced by a nuclear explosive is millions of times more per gram and the temperatures reached are in the tens of millions of degrees.
The energy of a nuclear explosive is initially released in the form of gamma rays and neutrons. When there is a surrounding material such as air, rock, or water, this radiation interacts with the material, rapidly heating it to an equilibrium temperature in about a microsecond. The hot material emits thermal radiation, mostly soft X-rays, which accounts for 75% of the energy of the explosion. In addition, the heating and vaporization of the surrounding material causes it to rapidly expand and the kinetic energy of this expansion accounts for almost all of the remaining energy.
When a nuclear detonation occurs in air near sea level, most of the soft X-rays in the primary thermal radiation are absorbed within a few feet. Some energy is reradiated in the ultraviolet, visible light and infrared spectrum, but most of the energy heats a spherical volume of air. This forms a fireball and its associated effects.
In a burst at high altitudes, where the air density is low, the soft X-rays travel long distances before they are absorbed. The energy is so diluted that the blast wave may be half as strong or less. The rest of the energy is dissipated as a more powerful thermal pulse.
In 1945 there was some initial speculation among the scientists developing the first nuclear weapons that there might be a possibility of igniting the Earth's atmosphere with a large enough nuclear explosion. This would concern a nuclear reaction of two nitrogen atoms forming a carbon and an oxygen atom, with release of energy. This energy would heat up the remaining nitrogen enough to keep the reaction going until all nitrogen atoms were consumed. This was, however, quickly shown to be unlikely enough to be considered impossible . Nevertheless, the notion has persisted as a rumour for many years.
The high temperatures and pressures cause gas to move outward radially in a thin, dense shell called "the hydrodynamic front." The front acts like a piston that pushes against and compresses the surrounding medium to make a spherically expanding shock wave. At first, this shock wave is inside the surface of the developing fireball, which is created in a volume of air by the X-rays. However, within a fraction of a second the dense shock front obscures the fireball, making the characteristic double pulse of light seen from a nuclear detonation. For air bursts at or near sea-level between 50-60% of the explosion's energy goes into the blast wave, depending on the size and the yield-to-weight ratio of the bomb. As a general rule, the blast fraction is higher for low yield and/or high bomb mass. Furthermore, it decreases at high altitudes because there is less air mass to absorb radiation energy and convert it into blast. This effect is most important for altitudes above 30 km, corresponding to <1 per cent of sea-level air density.
Much of the destruction caused by a nuclear explosion is due to blast effects. Most buildings, except reinforced or blast-resistant structures, will suffer moderate to severe damage when subjected to overpressures of only 35.5 kilopascals (kPa) (5.15 pounds-force per square inch or 0.35 atm).
Overpressure ranges from 1 to 50 psi of a 1 kiloton of TNT air burst as a function of burst height. The thin black curve indicates the optimum burst height for a given ground range.
The blast wind may exceed several hundred km/h. The range for blast effects increases with the explosive yield of the weapon and also depends on the burst altitude. Contrary to what one might expect from geometry the blast range is not maximal for surface or low altitude blasts but increases with altitude up to an "optimum burst altitude" and then decreases rapidly for higher altitudes. This is due to the nonlinear behaviour of shock waves. If the blast wave reaches the ground it is reflected. Below a certain reflection angle the reflected wave and the direct wave merge and form a reinforced horizontal wave, the so-called Mach stem (named after Ernst Mach). For each goal overpressure there is a certain optimum burst height at which the blast range is maximized. In a typical air burst, where the blast range is maximized for 5 to 20 psi (35 to 140 kPa), these values of overpressure and wind velocity noted above will prevail at a range of 0.7 km for 1 kiloton (kt) of TNT yield; 3.2 km for 100 kt; and 15.0 km for 10 megatons (Mt) of TNT.
Two distinct, simultaneous phenomena are associated with the blast wave in air:
* Static overpressure, i.e., the sharp increase in pressure exerted by the shock wave. The overpressure at any given point is directly proportional to the density of the air in the wave. * Dynamic pressures, i.e., drag exerted by the blast winds required to form the blast wave. These winds push, tumble and tear objects.
Most of the material damage caused by a nuclear air burst is caused by a combination of the high static overpressures and the blast winds. The long compression of the blast wave weakens structures, which are then torn apart by the blast winds. The compression, vacuum and drag phases together may last several seconds or longer, and exert forces many times greater than the strongest hurricane.
Acting on the human body, the shock waves cause pressure waves through the tissues. These waves mostly damage junctions between tissues of different densities (bone and muscle) or the interface between tissue and air. Lungs and the abdominal cavity, which contain air, are particularly injured. The damage causes severe haemorrhaging or air embolisms, either of which can be rapidly fatal. The overpressure estimated to damage lungs is about 70 kPa. Some eardrums would probably rupture around 22 kPa (0.2 atm) and half would rupture between 90 and 130 kPa (0.9 to 1.2 atm).
Blast Winds: The drag energies of the blast winds are proportional to the cubes of their velocities multiplied by the durations. These winds may reach several hundred kilometers per hour.
Nuclear weapons emit large amounts of electromagnetic radiation as visible, infrared, and ultraviolet light. The chief hazards are burns and eye injuries. On clear days, these injuries can occur well beyond blast ranges. The light is so powerful that it can start fires that spread rapidly in the debris left by a blast. The range of thermal effects increases markedly with weapon yield. Thermal radiation accounts for between 35-45% of the energy released in the explosion, depending on the yield of the device.
There are two types of eye injuries from the thermal radiation of a weapon:
Flash blindness is caused by the initial brilliant flash of light produced by the nuclear detonation. More light energy is received on the retina than can be tolerated, but less than is required for irreversible injury. The retina is particularity susceptible to visible and short wavelength infrared light, since this part of the electromagnetic spectrum is focused by the lens on the retina. The result is bleaching of the visual pigments and temporary blindness for up to 40 minutes.
On this victim of the atomic bombing of Hiroshima, the pattern of the kimono is clearly visible as burns on the skin.
A retinal burn resulting in permanent damage from scarring is also caused by the concentration of direct thermal energy on the retina by the lens. It will occur only when the fireball is actually in the individual's field of vision and would be a relatively uncommon injury. Retinal burns, however, may be sustained at considerable distances from the explosion. The apparent size of the fireball, a function of yield and range will determine the degree and extent of retinal scarring. A scar in the central visual field would be more debilitating. Generally, a limited visual field defect, which will be barely noticeable, is all that is likely to occur.
Since thermal radiation travels in straight lines from the fireball (unless scattered) any opaque object will produce a protective shadow. If fog or haze scatters the light, it will heat things from all directions and shielding will be less effective. Massive spread of radiation would also occur, which would be at the mercy of the wind.
When thermal radiation strikes an object, part will be reflected, part transmitted, and the rest absorbed. The fraction that is absorbed depends on the nature and color of the material. A thin material may transmit a lot. A light colored object may reflect much of the incident radiation and thus escape damage. The absorbed thermal radiation raises the temperature of the surface and results in scorching, charring, and burning of wood, paper, fabrics, etc. If the material is a poor thermal conductor, the heat is confined to the surface of the material.
Actual ignition of materials depends on how long the thermal pulse lasts and the thickness and moisture content of the target. Near ground zero where the light exceeds 125 J/cm², what can burn, will. Farther away, only the most easily ignited materials will flame. Incendiary effects are compounded by secondary fires started by the blast wave effects such as from upset stoves and furnaces.
In Hiroshima, a tremendous fire storm developed within 20 minutes after detonation and destroyed many more buildings and homes. A fire storm has gale force winds blowing in towards the center of the fire from all points of the compass. It is not, however, a phenomenon peculiar to nuclear explosions, having been observed frequently in large forest fires and following incendiary raids during World War II.
Gamma rays from a nuclear explosion produce high energy electrons through Compton scattering. These electrons are captured in the earth's magnetic field, at altitudes between twenty and forty kilometers, where they resonate. The oscillating electric current produces a coherent electromagnetic pulse (EMP) which lasts about one millisecond. Secondary effects may last for more than a second.
The pulse is powerful enough to cause long metal objects (such as cables) to act as antennae and generate high voltages when the pulse passes. These voltages, and the associated high currents, can destroy unshielded electronics and even many wires. There are no known biological effects of EMP. The ionized air also disrupts radio traffic that would normally bounce off the ionosphere.
One can shield electronics by wrapping them completely in conductive mesh, or any other form of Faraday cage. Of course radios cannot operate when shielded, because broadcast radio waves can't reach them.
The largest-yield nuclear devices are designed for this use. An air burst at the right altitude could produce
The mushroom cloud from the first "true" Soviet hydrogen bomb test in 1955.
About 5% of the energy released in a nuclear air burst is in the form of ionizing radiation: neutrons, gamma rays, alpha particles, and electrons moving at incredible speeds, but with different speeds that can be still far away from the speed of light (alpha particles). The neutrons result almost exclusively from the fission and fusion reactions, while the initial gamma radiation includes that arising from these reactions as well as that resulting from the decay of short-lived fission products.
The intensity of initial nuclear radiation decreases rapidly with distance from the point of burst because the radiation spreads over a larger area as it travels away from the explosion. It is also reduced by atmospheric absorption and scattering.
The character of the radiation received at a given location also varies with distance from the explosion. Near the point of the explosion, the neutron intensity is greater than the gamma intensity, but with increasing distance the neutron-gamma ratio decreases. Ultimately, the neutron component of initial radiation becomes negligible in comparison with the gamma component. The range for significant levels of initial radiation does not increase markedly with weapon yield and, as a result, the initial radiation becomes less of a hazard with increasing yield. With larger weapons, above fifty kt (200 TJ), blast and thermal effects are so much greater in importance that prompt radiation effects can be ignored.
The neutron radiation serves to transmute the surrounding matter, often rendering it radioactive. When added to the dust of radioactive material released by the bomb itself, a large amount of radioactive material is released into the environment. This form of radioactive contamination is known as nuclear fallout and poses the primary risk of exposure to ionizing radiation for a large nuclear weapon.
The pressure wave from an underground explosion will propagate through the ground and cause a minor earthquake.  Theory suggests that a nuclear explosion could trigger fault rupture and cause a major quake at distances within a few tens of kilometers from the shot point. 
Summary of the effects
1) For the direct radiation effects the slant range instead of the ground range is shown here, because some effects are not given even at ground zero for some burst heights. If the effect occurs at ground zero the ground range can simply be derived from slant range and burst altitude (Pythagorean theorem).
2) "Acute radiation syndrome" corresponds here to a total dose of one gray, "lethal" to ten grays. Note that this is only a rough estimate since biological conditions are neglected here.
As the fireball rises through still air, it takes on the flow pattern of a vortex ring with incandescent material in the vortex core as seen in certain photographs. At the explosion of nuclear bombs sometimes lightning discharges occur. Not related to the explosion itself, often there are smoke trails seen in photographs of nuclear explosions. These are formed from rockets emitting smoke launched before detonation. The smoke trails are used to determine the position of the shockwave, which is invisible, in the milliseconds after detonation through the refraction of light, which causes an optical break in the smoke trails as the shockwave passes. A fizzle occurs if the nuclear chain reaction is not sustained long enough to cause an explosion. This can happen if, for example, the yield of the fissile material used is too low, the compression explosives around fissile material misfire or the neutron initiator fails.
This is highly dependent on factors such as proximity to the blast and the direction of the wind carrying fallout.
There has also been controversy as to whether cockroaches would survive a nuclear blast. The answer is that they have a high degree of survivability, since they are resistant to radiation and can burrow underground for extended periods of time and avoid fallout. However, cockroaches would be instantly incinerated by the initial blast. 
Nuclear espionage is the purposeful giving of state secrets regarding nuclear weapons to other states without authorization (espionage). During the history of nuclear weapons there have been many cases of known nuclear espionage, and also many cases of suspected or alleged espionage. Because nuclear weapons are generally considered the most important of state secrets, all nations with nuclear weapons have strict restrictions against the giving of information relating to nuclear weapon design, stockpiles, delivery systems, and deployment. States are also limited in their making public of weapons information by non-proliferation agreements.
During the Manhattan Project, the joint effort during World War II by the United States, the United Kingdom, and Canada to create the first nuclear weapons, there were many instances of nuclear espionage in which project scientists or technicians channeled information about bomb development and design to the Soviet Union. These people are often referred to as the Atomic Spies, and their work continued into the early Cold War. Because most of these cases became well-known in the context of the anti-Communist 1950s, there has been long-standing dispute over the exact details of these cases, though some of this was settled with the making public of the VENONA Project transcripts, which were intercepted and decrypted messages between Soviet agents and the Soviet government. Some issues remain unsettled, however.
Klaus Fuchs is considered to have been the most valuable of the Atomic Spies during the Manhattan Project.
The most prominent of these included:
* Klaus Fuchs – German refugee theoretical physicist who worked with the British delegation at Los Alamos during the Manhattan Project. He was eventually discovered, confessed, and sentenced to jail in Britain. He was later released, and he emigrated to East Germany. Because of his close connection to many aspects of project activities, and his extensive technical knowledge, he is considered to have been the most valuable of the "Atomic Spies" in terms of the information he gave to the Soviet Union about the American fission bomb program. He also gave early information about the American hydrogen bomb program but since he was not present at the time that the successful Teller-Ulam design was discovered, his information on this is not thought to have been of much value. * Theodore Hall – a young American physicist at Los Alamos, whose identity as a spy was not revealed until very late in the twentieth century. He was never arrested in connection to his espionage work, though seems to have admitted to it in later years to reporters and to his family. * David Greenglass – an American machinist at Los Alamos during the Manhattan Project. Greenglass confessed that he gave crude schematics of lab experiments to the Russians during World War II. Some aspects of his testimony against his sister and brother-in-law (the Rosenbergs, see below) are now thought to have been fabricated in an effort to keep his own wife from prosecution. Greenglass confessed to his espionage and was given a long prison term. * Ethel and Julius Rosenberg – Americans who were supposedly involved in coordinating and recruiting an episonage network which included David Greenglass. While most scholars believe that Julius was likely involved in some sort of network, whether or not Ethel was involved or cogniscent of the activities remains a matter of dispute. Julius and Ethel refused to confess to any charges, and were convicted and executed. * Harry Gold – American, confessed to acting as a courier for Greenglass and Fuchs.
A drawing of an implosion nuclear weapon design by David Greenglass, illustrating what he supposedly gave the Rosenbergs to pass on to the Soviet Union.
Whether the espionage information significantly aided the speed of the Soviet atomic bomb project is also disputed. While some of the information given, such as the highly technical theoretical information given by Klaus Fuchs, would be thought to have certainly aided in developing a nuclear weapon, the manner in which the heads of the Soviet bomb project, Igor Kurchatov and Lavrenty Beria, actually used the information has led later scholars to doubt it having had a role in increasing the speed of development. According to this account, Kurchatov and Beria used the information primarily as a "check" against their own scientists' work, and did not liberally share the information with them, distrusting both their own scientists as well as the espionage information. Later scholarship has also shown that the decisive force in early Soviet development was not problems in weapons design, but, as in the Manhattan Project, the difficulty in procuring fissile materials, especially as the Soviet Union had no uranium deposits known when it began its program (unlike the United States).
In 1986, a former technician, Mordechai Vanunu, at the Israeli nuclear facility near Dimona revealed information about the Israeli nuclear weapon program to the British press, confirming widely-held notions that Israel had an advanced and secretive nuclear weapons program and stockpile. Israel has never acknowledged or denied having a weapons program, and Vanunu was abducted and smuggled to Israel, where he was tried in camera and convicted of treason and espionage. Whether Vanunu was truly involved in espionage, per se, is debated: Vanunu and his supporters claim that he should be regarded as a whistle-blower (someone who was exposing a secretive and illegal practice), while his opponents see him as a traitor and his divulgance of information as aiding enemies of the Israeli state. The politics of the case are hotly disputed.
People's Republic of China
In a 1999 report of the United States House of Representatives Select Committee on U.S. National Security and Military/Commercial Concerns with the People's Republic of China, chaired by Rep. Christopher Cox (known as the Cox Report), it was revealed that U.S. security agencies believed that on-going nuclear espionage by the People's Republic of China (PRC) at U.S. nuclear weapons design laboratories, especially Los Alamos National Laboratory, Lawrence Livermore National Laboratory, Oak Ridge National Laboratory, and Sandia National Laboratories. According to the report, the PRC had "stolen classified information on all of the United States' most advanced thermonuclear warheads" since the 1970s, and included the design of advanced miniaturized thermonuclear warheads (which can be used on MIRV weapons), the neutron bomb, and "weapons codes" which allow for computer simulations of nuclear testing (and allow the PRC to advance their weapon development without testing themselves). The United States was apparently unaware of this until 1995.
The investigations described in the report eventually led to the arrest of Wen Ho Lee, a scientist at Los Alamos, which accused him of giving weapons information to the PRC. The case against Lee eventually fell apart, however, and he was eventually charged only with mishandling of data. Other people and groups arrested or fined were scientist Peter Lee (no relation), who was arrested for allegedly giving submarine radar secrets to China, and Loral Space & Communications and Hughes Electronics who gave China missile secrets. No other arrests regarding the theft of the nuclear designs have been made. The issue was a considerable scandal at the time.
Design information about the W88 warhead, a miniaturized variant of the Teller-Ulam design, was allegedly stolen by PRC agents.
In January 2004, Dr. Abdul Qadeer Khan, a Pakistani nuclear scientist, confessed to selling restricted nuclear weapons technology to Libya, Iran, and North Korea. According to his testimony and reports from intelligence agencies, Khan sold designs for gas centrifuges (used for uranium enrichment), Chinese designs for a nuclear warhead, and sold centrifuges themselves to these three countries. Khan had previously been indicated as having taken gas centrifuge designs from a uranium enrichment company in the Netherlands (URENCO) which he used to jump-start Pakistan's own nuclear weapons program. On February 5, 2004, the president of Pakistan, General Pervez Musharraf, announced that he had pardoned Khan. Pakistan's government claims they had no part in the espionage, but refuses to turn Khan over for questioning by the International Atomic Energy Agency.
On February 4, 2004, Khan appeared on Pakistani national television and confessed to running an international ring for nuclear proliferation. He was pardoned the next day by Pakistani President Musharraf, but has since then remained under house arrest.
Biological warfare (BW), also known as germ warfare, is the use of any pathogen (bacterium, virus or other disease-causing organism) or toxin found in nature as a weapon of war. BW may be intended to kill, incapacitate or seriously impede an adversary. It may also be defined as the material; or defense against such employment.
The creation and stockpiling of biological weapons ("offensive BW") was outlawed by the 1972 Biological Weapons Convention (BWC), signed by over 100 countries. The BWC remains in force. The rationale behind the agreement is to avoid the devastating impact of a successful biological attack which could conceivably result in thousands, possibly even millions, of deaths and cause severe disruptions to societies and economies. Oddly enough, the convention prohibits only creation and storage, but not usage, of these weapons. However, the consensus among military analysts is that, except in the context of bioterrorism, BW is of little military use. Many countries pursue "defensive BW" research (defensive or protective applications) which are not prohibited by the BWC.
As a tactical weapon, the main military problem with a BW attack is that it would take days to be effective, and therefore, unlike a nuclear or chemical attack, would not immediately stop an opposing force. As a strategic weapon, BW is again militarily problematic, because it is difficult to prevent the attack from spreading, either to allies or to the attacker, and while an attack is taking effect, the opponent can undertake massive retaliation.
Biological warfare has been practiced repeatedly throughout history. Before the 20th century, the use of biological agents took three major forms:
* Deliberate poisoning of food and water with infectious material * Use of microorganisms, toxins or animals, living or dead, in a weapon system * Use of biologically inoculated fabrics
The Ancient World
During the 6th Century B.C, the Assyrians poisoned enemy wells with a fungus that would make the enemy delusional. In 184 B.C, Hannibal of Carthage had clay pots filled with venomous snakes and instructed his soldiers to throw the pots onto the decks of Pergamene ships.
During the Middle Ages, victims of the bubonic plague were used for biological attacks, often by flinging their corpses and excrement over castle walls using catapults. In 1346, the bodies of Tartar soldiers who had died of plague were thrown over the walls of the besieged Crimean city of Kaffa (now Theodosia). It has been speculated that this operation could have been responsible for the advent of the Black Death in Europe, though this is very unlikely (the disease carrying fleas don't linger on a cold corpse)
Though not germ warfare, which implies the deliberate use of germs against an enemy, the inadvertent spread of diseases across the Atlantic during the European age of exploration did tremendous damage to the indigenous populations of North and South America. The effects of the "Columbian exchange" of diseases upon the Native Americans was catastrophic, reducing the population of affected tribes by as much as 50-90%. When the Pilgrims arrived in the New World in 1620, the native population of the Plymouth area had already been virtually eliminated by diseases that traveled with European fishing expeditions to the waters of the Northeast. The Spanish conquest of the Aztecs in Mexico and the English predominance in North America would not have been nearly as rapid if not for the devastating effect of diseases that had been previously unknown in the Americas and against which the local populations had built up no immunities.
The last known incident of using plague corpses for biological warfare occurred in 1710, when Russian forces attacked the Swedes by flinging plague-infected corpses over the city walls of Reval (Tallinn).
The Native American population was decimated after contact with the Old World due to the introduction of many different fatal diseases. There is, however, only one documented case of alleged germ warfare, involving British commander Lord Jeffrey Amherst and a Swiss officer, Henry Bouquet, whose correspondence included a reference to the idea of giving smallpox-infected blankets to Indians near Fort Pitt during the French and Indian War (1756-1763). Historians have been unable to establish whether or not this plan was implemented, particularly in light of the fact that smallpox was already present in the region. (Attempts by missionaries to provide inoculation to local tribespeople were usually met with suspicion, thus leaving the native population completely vulnerable to epidemics.) Despite the lack of historical evidence, the claim that British and American soldiers used germ warfare against North American tribes has remained fairly strong in certain oral traditions and in popular culture.
Native peoples in Aptos gave Spaniards gifts of freshly cut flowers wrapped in leaves of poison oak.
During the American Civil War, General Sherman reported that Confederate forces shot farm animals in ponds upon which the Union depended for drinking water.
The 20th Century
Use of such weapons was banned in international law by the Geneva Protocol of 1925. The 1972 Biological and Toxin Weapons Convention extended the ban to almost all production, storage and transport. However, the Soviet Union continued research and production of offensive biological weapons in a program called biopreparat, despite having signed the Biological and Toxin Weapons Convention. The United States was unaware of the program until Dr. Kanatjan Alibekov, the first deputy director of biopreparat defected in 1992. It is, however, believed that since the signing of the convention the number of countries capable of producing such weapons has increased.
During the Sino-Japanese War (1937-1945) and World War II, Unit 731 of the Imperial Japanese Army conducted human experimentation on thousands, mostly Chinese and Korean. In military campaigns, the Japanese army used biological weapons on Chinese soldiers and civilians. This employment was largely viewed as ineffective due to inefficient delivery systems. However, new information has surfaced within the last decade, which alleges a more active Japanese usage. For example, firsthand accounts testify the Japanese infected civilians through the distribution of plagued foodstuffs, such as dumplings and vegetables. There are also reports of contaminated water supplies. Such estimates report over 580,000 victims, largely due to plague and cholera outbreaks. In addition, repeated seasonal outbreaks after the conclusion of the war bring the death toll much higher.
In response to suspected biological weapons development in Germany and Japan, the United States, United Kingdom, and Canada initiated a BW development program in 1941 that resulted in the weaponization of anthrax, brucellosis, and botulism toxin. The center for U.S. military BW research was Fort Detrick, Maryland. Some biological and chemical weapons research was also conducted at "Dugway Proving Grounds" in Utah. Research carried out in the United Kingdom during World War II left Gruinard island in Scotland contaminated with anthrax for the next 48 years. During WWII, US conscientious objectors were used as test subjects for biological agents in a program known as Operation Whitecoat.
E120 biological bomblet, developed before the U.S. signed the Biological and Toxic Weapons Convention
Considerable research on the topic was performed by the United States, the Soviet Union (see Biopreparat), and probably other major nations throughout the Cold War era, though it is generally believed that such weapons were never used. This view was challenged by China and North Korea, who accused the United States of large-scale field testing of biological weapons, including the use of disease-carrying insects, against them during the Korean War (1950-1953). Their accusation is substantiated by Stephen Endicott and Edward Hagerman in 'The United States and Biological Warfare: secrets of the early Cold War and Korea' (Bloomington, Indiana University Press, 1998). In 1972, the U.S. signed the Biological and Toxic Weapons Convention, which banned "development, production and stockpiling of microbes or their poisonous products except in amounts necessary for protective and peaceful research." By 1996, 137 countries had signed the treaty.
In 1986, the U.S. government spent US$42 million on research for developing infectious diseases and toxins, ten times more money than was spent in 1981. The money went to 24 U.S. universities in hopes of developing strains of anthrax, Rift Valley fever, Japanese encephalitis, tularemia, shigella, botulin, and Q fever. When the Biology Department at MIT voted to refuse Pentagon funds for biotech research, the Reagan administration forced it to reverse its decision by threatening to cut off other funds.
There have been reports that the United States Army has been developing weapons-grade anthrax spores at Dugway Proving Ground, a chemical and biological defense testing facility in Utah, since at least as early as 1992. Under the BWC, nations are permitted to develop small amounts of BW agents for the purpose of defensive research. The United States has maintained a stated national policy of never using biological weapons under any circumstances since November 1969 President Nixon.
Beginning on September 18, 2001, several letters were received by members of the U.S. Congress and media outlets containing anthrax. The attack killed five people. The identity of the perpetrator remains unknown as of 2006.
References for this section include (Eitzen & Takafuji, 1997)
Biological weapons characteristics
The international biological hazard symbol. It represents a mature cellular organism in the background which has produced three partially formed offspring in the foreground
Ideal characteristics of biological weapons are high infectivity, high potency, availability of vaccines, and delivery as an aerosol.
Diseases most likely to be considered for use as biological weapons are contenders because of their lethality (if delivered efficiently), and robustness (making aerosol delivery feasible).
The biological agents used in biological weapons can often be manufactured quickly and easily. The primary difficulty is not the production of the biological agent but delivery in an infective form to a vulnerable target.
For example, anthrax is considered an effective agent for several reasons. First, it forms hardy spores, perfect for dispersal aerosols. Second, pneumonic (lung) infections of anthrax usually do not cause secondary infections in other people. Thus, the effect of the agent is usually confined to the target. A pneumonic anthrax infection starts with ordinary "cold" symptoms and quickly becomes lethal, with a fatality rate that is 80% or higher. Finally, friendly personnel can be protected with suitable antibiotics.
A mass attack using anthrax would require the creation of aerosol particles of 1.5 to 5 micrometres. Too large and the aerosol would be filtered out by the respiratory system. Too small and the aerosol would be inhaled and exhaled. Also, at this size, nonconductive powders tend to clump and cling because of electrostatic charges. This hinders dispersion. So, the material must be treated with silica to insulate and discharge the charges. The aerosol must be delivered so that rain and sun does not rot it, and yet the human lung can be infected. There are other technological difficulties as well.
Diseases considered for weaponization, or known to be weaponized include anthrax, Ebola, Bubonic Plague, Cholera, Tularemia, Brucellosis, Q fever, Machupo, Coccidioides mycosis, Glanders, Melioidosis, Shigella, Rocky Mountain Spotted Fever, Typhus, Psittacosis, Yellow Fever, Japanese B Encephalitis, Rift Valley Fever, and Smallpox. Naturally-occurring toxins that can be used as weapons include Ricin, SEB, Botulism toxin, Saxitoxin, and many Mycotoxins. The organisms causing these diseases are known as select agents. Their possession, use, and transfer are regulated by the Centers for Disease Control and Prevention's Select Agent Program.
Attacking crops and animals
Biological warfare can also specifically target plants to destroy crops or defoliate vegetation. The United States and Britain discovered plant growth regulators (i.e., herbicides) during the Second World War, and initiated a Herbicidal Warfare program that was eventually used in Malaya and Vietnam in counter insurgency. Though herbicides are chemicals, they are often grouped with biological warfare as bioregulators in a similar manner as biotoxins.Scorched earth tactics or destroying livestock and farmland were carried out in the Vietnam war and Eelam War in Sri Lanka.
The United States developed an anti-crop capability during the Cold War that used plant diseases (bioherbicides, or mycoherbicides) for destroying enemy agriculture. It was believed that destruction of enemy agriculture on a strategic scale could thwart Sino-Soviet aggression in a general war. Diseases such as wheat blast and rice blast were weaponized in aerial spray tanks and cluster bombs for delivery to enemy water sheds in agricultural regions to initiate epiphytotics (epidemics among plants). When the United States renounced its offensive biological warfare program in 1969 and 1970, the vast majority of its biological arsenal was composed of these plant diseases.
Attacking animals is another area of biological warfare intended to eliminate animal resources for transportation and food. In the First World War German agents were arrested attempting to inoculate draft animals with anthrax, and they were believed to be responsible for outbreaks of glanders in horses and mules. The British tainted small feed cakes with anthrax in the Second World War as a potential means of attacking German cattle for food denial, but never employed the weapon. In the 1950s the United States had a field trial with hog cholera.
The role of public health departments and disease surveillance
It is important to note that all of the classical and modern biological weapons organisms are animal diseases, the only exception being smallpox. Thus, in any use of biological weapons, it is highly likely that animals will become ill either simultaneously with, or perhaps earlier than humans. Indeed, in the largest biological weapons "accident" known -- the anthrax outbreak in Sverdlovsk (now Yekaterinburg) in the Soviet Union in 1979, sheep became ill with anthrax as far as 200 kilometers from the release point of the organism from a military facility in the southeastern portion of the city (known as Compound 19 and still off limits to visitors today).
Thus, a robust surveillance system involving human clinicians and veterinarians may identify a bioweapons attack early in the course of an epidemic, permitting the prophylaxis of disease in the vast majority of people (and/or animals) exposed but not yet ill. For example in the case of anthrax, it is likely that by 24 - 36 hours after an attack, some small percentage of individuals (those with compromised immune system or who had received a large dose of the organism due to proximity to the release point) will become ill with classical symptoms and signs (including a virtually unique chest X-ray finding, often recognized by public health officials if they receive timely reports). By making these data available to local public health officials in real time, most models of anthrax epidemics indicate that more than 80% of an exposed population can receive antibiotic treatment before becoming symptomatic, and thus avoid the high mortality of the disease.
Identification of bioweapons
The growing threat of biowarfare agents and bioterrorism has led to the development of specific field tools that perform on-the-spot analysis and identification of encountered suspect materials. One such technology, being developed by researchers from the Lawrence Livermore National Laboratory (LLNL), employs a "sandwich immunoassay", in which fluorescent dye-labeled antibodies aimed at specific pathogens are attached to silver and gold nanowires. Researchers at Ben Gurion University in Israel are developing a different device called the BioPen, essentially a "Lab-in-a-Pen", which can detect known biological agents in under 20 minutes using an adaptation of the ELISA, a similar widely employed immunological technique, that in this case incorporates fiber optics.
Chemical warfare is warfare (and associated military operations) using the toxic properties of chemical substances to kill, injure or incapacitate an enemy.
Chemical warfare is different from the use of conventional weapons or nuclear weapons because the destructive effects of chemical weapons are not primarily due to any explosive force. The offensive use of living organisms (such as anthrax) is considered to be biological warfare rather than chemical warfare; the use of nonliving toxic products produced by living organisms (e.g., toxins such as botulinum toxin, ricin, or saxitoxin) is considered chemical warfare under the provisions of the Chemical Weapons Convention. Under this Convention, any toxic chemical, regardless of its origin, is considered as a chemical weapon unless it is used for purposes that are not prohibited (an important legal definition, known as the General Purpose Criterion).
About 70 different chemicals have been used or stockpiled as Chemical Weapons (CW) agents during the 20th century. Chemical weapons are classified as weapons of mass destruction by the United Nations, and their production and stockpiling was outlawed by the Chemical Weapons Convention of 1993. Under the Convention, chemicals that are toxic enough to be used as chemical weapons, or may be used to manufacture such chemicals, are divided into three groups according to their purpose and treatment:
* Schedule 1 – Have few, if any, legitimate uses. These may only be produced or used for research, medical, pharmaceutical or protective purposes (i.e. testing of chemical weapons sensors and protective clothing). Examples include nerve agents, ricin, lewisite and mustard gas. Any production over 100 g must be notified to the OPCW and a country can have a stockpile of no more than one tonne of these chemicals. * Schedule 2 – Have no large-scale industrial uses, but may have legitimate small-scale uses. Examples include dimethyl methylphosphonate, a precursor to sarin but which is also used as a flame retardant and Thiodiglycol which is a precursor chemical used in the manufacture of mustard gas but is also widely used as a solvent in inks. * Schedule 3 – Have legitimate large-scale industrial uses. Examples include phosgene and chloropicrin. Both have been used as chemical weapons but phosgene is an important precursor in the manufacture of plastics and chloropicrin is used as a fumigant. Any plant producing more than 30 tonnes per year must be notified to, and can be inspected by, the OPCW.
Chemical warfare technology
Although crude chemical warfare has been employed in many parts of the world for thousands of years, "modern" chemical warfare began during World War I (see main article - Poison gas in World War I). Initially, only well-known commercially available chemicals and their variants were used. These included chlorine and phosgene gas. The methods of dispersing these agents during battle were relatively unrefined and inefficient.
Germany, the first side to employ chemical warfare on the battlefield, simply opened canisters of chlorine upwind of the opposing side and let the prevailing winds do the dissemination. Soon after, the French modified artillery munitions to contain phosgene – a much more effective method that became the principal means of delivery.
Since the development of modern chemical warfare in World War I, nations have pursued research and development on chemical weapons that falls into four major categories: new and more deadly agents; more efficient methods of delivering agents to the target (dissemination); more reliable means of defense against chemical weapons; and more sensitive and accurate means of detecting chemical agents.
Chemical weapon agents
A chemical used in warfare is called a chemical weapon agent (CWA). About 70 different chemicals have been used or stockpiled as chemical weapon agents during the 20th century and the 21st century. These agents may be in liquid, gas or solid form. Liquid agents are generally designed to evaporate quickly; such liquids are said to be volatile or have a high vapor pressure. Many chemical agents are made volatile so they can be dispersed over a large region quickly.
The earliest target of chemical weapon agent research was not toxicity, but development of agents that can affect a target through the skin and clothing, rendering protective gas masks useless. In July 1917, the Germans first employed mustard gas, the first agent that circumvented gas masks. Mustard gas easily penetrates leather and fabric to inflict painful burns on the skin.
Chemical weapon agents are divided into lethal and incapacitating categories. A substance is classified as incapacitating if less than 1/100 of the lethal dose causes incapacitation, e.g., through nausea or visual problems. The distinction between lethal and incapacitating substances is not fixed, but relies on a statistical average called the LD.
A Swedish Army soldier wearing a chemical agent protective suit (C-vätskeskydd) and his protection mask (skyddsmask 90).
All chemical weapon agents are classified according to their persistency, a measure of the length of time that a chemical agent remains effective after dissemination. Chemical agents are classified as persistent or nonpersistent.
Agents classified as nonpersistent lose effectiveness after only a few minutes or hours. Purely gaseous agents such as chlorine are nonpersistent, as are highly volatile agents such as sarin and most other nerve agents. Tactically, nonpersistent agents are very useful against targets that are to be taken over and controlled very quickly. Generally speaking, nonpersistent agents present only an inhalation hazard.
By contrast, persistent agents tend to remain in the environment for as long as a week, complicating decontamination. Defense against persistent agents requires shielding for extended periods of time. Non-volatile liquid agents, such as blister agents and the oily VX nerve agent, do not easily evaporate into a gas, and therefore present primarily a contact hazard.
Classes of chemical weapon agents
Chemical weapon agents are organized into several categories according to the manner in which they affect the human body. The names and number of categories varies slightly from source to source, but in general, types of chemical weapon agents are as follows:
Classes of chemical weapon agents [Klikni na thumbnail za vecu sliku]
There are other chemicals used militarily that are not technically considered to be "chemical weapon agents," such as:
* Defoliants that destroy vegetation, but are not immediately toxic to human beings. (Agent Orange, for instance, used by the United States in Vietnam, contained dioxins and is known for its long-term cancer effects and for causing genetic damage leading to serious birth deformities.) * Incendiary or explosive chemicals (such as napalm, extensively used by the United States in Vietnam, or dynamite) because their destructive effects are primarily due to fire or explosive force, and not direct chemical action. * Viruses, bacteria, or other organisms. Their use is classified as biological warfare.
Chemical weapon designations
Most chemical weapons are assigned a one- to three-letter "NATO weapon designation" in addition to, or in place of, a common name. Binary munitions, in which precursors for chemical weapon agents are automatically mixed in shell to produce the agent just prior to its use, are indicated by a "-2" following the agent's designation (for example, GB-2 and VX-2).
Some examples are given below:
Chemical agent delivery
The most important factor in the effectiveness of chemical weapons is the efficiency of its delivery, or dissemination, to a target. The most common techniques include munitions (such as bombs, projectiles, warheads) that allow dissemination at a distance and spray tanks which disseminate from low-flying aircraft. Developments in the techniques of filling and storage of munitions have also been important.
Although there have been many advances in chemical weapon delivery since World War I, it is still difficult to achieve effective dispersion. The dissemination is highly dependent on atmospheric conditions because many chemical agents act in gaseous form. Thus, weather observations and forecasting are essential to optimize weapon delivery and reduce the risk of injuring friendly forces.
Dispersion is the simplest technique of delivering an agent to its target. It consists of placing the chemical agent upon or adjacent to a target immediately before dissemination, so that the material is most efficiently used.
World War I saw the earliest implementation of this technique, when German forces at Ypres simply opened cylinders of chlorine and allowed the wind to carry the gas across enemy lines. While simple, this technique had numerous disadvantages. Moving large numbers of heavy gas cylinders to the front-line positions from where the gas would be released was a lengthy and difficult logistical task. Stockpiles of cylinders had to be stored at the front line, posing a great risk if hit by artillery shells. Gas delivery depended greatly on wind speed and direction. If the wind was fickle, as at Loos, the gas could blow back, causing friendly casualties. Gas clouds gave plenty of warning, allowing the enemy time to protect themselves, though many soldiers found the sight of a creeping gas cloud unnerving. Also gas clouds had limited penetration, capable only of affecting the front-line trenches before dissipating. Although it produced limited results in World War I, this technique shows how simple chemical weapon dissemination can be.
Shortly after this "open canister" dissemination, French forces developed a technique for delivery of phosgene in a non-explosive artillery shell. This technique overcame many of the risks of dealing with gas in cylinders. First, gas shells were independent of the wind and increased the effective range of gas, making any target within reach of guns vulnerable. Second, gas shells could be delivered without warning, especially the clear, nearly odorless phosgene — there are numerous accounts of gas shells, landing with a "plop" rather than exploding, being initially dismissed as dud high explosive or shrapnel shells, giving the gas time to work before the soldiers were alerted and took precautions.
The major drawback of artillery delivery was the difficulty of achieving a killing concentration. Each shell had a small gas payload and an area would have to be subjected to saturation bombardment to produce a cloud to match cylinder delivery. A British solution to the problem was the Livens Projector. This was effectively a large-bore mortar, dug into the ground that used the gas cylinders themselves as projectiles - firing a 14 kg cylinder up to 1500 m. This combined the gas volume of cylinders with the range of artillery.
Over the years, there were some refinements in this technique. In the 1950s and early 1960s, chemical artillery rockets contained a multitude of submunitions, so that a large number of small clouds of the chemical agent would form directly on the target.
Dispersion of chlorine in World War I
Thermal dissemination is the use of explosives or pyrotechnics to deliver chemical agents. This technique, developed in the 1920s, was a major improvement over earlier dispersal techniques, in that it allowed significant quantities of an agent to be disseminated over a considerable distance. Thermal dissemination remains the principal method of disseminating chemical agents today.
Most thermal dissemination devices consist of a bomb or projectile shell that contains a chemical agent and a central "burster" charge; when the burster detonates, the agent is expelled laterally.
Thermal dissemination devices, though common, are not particularly efficient. First, a percentage of the agent is lost by incineration in the initial blast and by being forced onto the ground. Second, the sizes of the particles vary greatly because explosive dissemination produces a mixture of liquid droplets of variable and difficult to control sizes.
The efficacy of thermal detonation is greatly limited by the flammability of some agents. For flammable aerosols, the cloud is sometimes totally or partially ignited by the disseminating explosion in a phenomenon called flashing. Explosively disseminated VX will ignite roughly one third of the time. Despite a great deal of study, flashing is still not fully understood, and a solution to the problem would be a major technological advance.
Despite the limitations of central bursters, most nations use this method in the early stages of chemical weapon development, in part because standard munitions can be adapted to carry the agents.
An American-made MC-1 gas bomb
Aerodynamic dissemination is the non-explosive delivery of a chemical agent from an aircraft, allowing aerodynamic stress to disseminate the agent. This technique is the most recent major development in chemical agent dissemination, originating in the mid-1960s.
This technique eliminates many of the limitations of thermal dissemination by eliminating the flashing effect and theoretically allowing precise control of particle size. In actuality, the altitude of dissemination, wind direction and velocity, and the direction and velocity of the aircraft greatly influence particle size. There are other drawbacks as well; ideal deployment requires precise knowledge of aerodynamics and fluid dynamics, and because the agent must usually be dispersed within the boundary layer (less than 200–300 ft above the ground), it puts pilots at risk.
Significant research is still being applied toward this technique. For example, by modifying the properties of the liquid, its breakup when subjected to aerodynamic stress can be controlled and an idealized particle distribution achieved, even at supersonic speed. Additionally, advances in fluid dynamics, computer modeling, and weather forecasting allow an ideal direction, speed, and altitude to be calculated, such that weapon agent of a predetermined particle size can predictably and reliably hit a target.
Soviet chemical weapons canisters from a stockpile in Albania
Sociopolitical climate of chemical warfare
ARMIS BELLA NON VENENIS GERI
"War is fought with weapons, not with poisons"
While the study of chemicals and their military uses was widespread in China, the use of toxic materials has historically been viewed with mixed emotions and some disdain in the West.
One of the earliest reactions to the use of chemical agents was from Rome. Struggling to defend themselves from the Roman legions, Germanic tribes poisoned the wells of their enemies, with Roman jurists having been recorded as declaring "armis bella non venenis geri", meaning "war is fought with weapons, not with poisons."
Before 1915 the use of poisonous chemicals in battle was typically the result of local initiative, and not the result of an active government chemical weapons program. There are many reports of the isolated use of chemical agents in individual battles or sieges, but there was no true tradition of their use outside of incendiaries and smoke. Despite this tendency, there have been several attempts to initiate large-scale implementation of poison gas in several wars, but with the notable exception of World War I, the responsible authorities generally rejected the proposals for ethical reasons.
For example, in 1854 Lyon Playfair, a British chemist, proposed using a cyanide-filled artillery shell against enemy ships during the Crimean War. The British Ordnance Department rejected the proposal as "as bad a mode of warfare as poisoning the wells of the enemy."
Efforts to eradicate chemical weapons
* August 27, 1874: The Brussels Declaration Concerning the Laws and Customs of War is signed, specifically forbidding the "employment of poison or poisoned weapons." * September 4, 1900: The Hague Conference, which includes a declaration banning the "use of projectiles the object of which is the diffusion of asphyxiating or deleterious gases," enters into force. * February 6, 1922: After World War I, the Washington Arms Conference Treaty prohibited the use of asphyxiating, poisonous or other gases. It was signed by the United States, Britain, Japan, France, and Italy, but France objected to other provisions in the treaty and it never went into effect. * September 7, 1929: The Geneva Protocol enters into force, prohibiting the use of poison gas and bacteriological methods of warfare. As of 2004, there are 132 signatory nations. * May 1991: President George H.W. Bush unilaterally commits the United States to destroying all chemical weapons and to renounce the right to chemical weapon retaliation. o The U.S. Congress has since passed legislation requiring the destruction of the entire stockpile by December 31, 2004. Official U.S. policy is to support the Chemical Weapons Convention as a means to achieve a global ban on this class of weapons and to halt their proliferation. * April 29, 1997: The Chemical Weapons Convention enters into force, augmenting the Geneva Protocol of 1925 by outlawing the production, stockpiling and use of chemical weapons.
Chemical weapon proliferation
Despite numerous efforts to reduce or eliminate them, some nations continue to research and/or stockpile chemical weapon agents. To the right is a summary of the nations that have either declared weapon stockpiles or are suspected of secretly stockpiling or possessing CW research programs. Notable examples include China and Israel.
According to the testimony of Assistant Secretary of State for Intelligence and Research Carl W. Ford before the Senate Committee on Foreign Relations, it is very probable that China has an advanced chemical warfare program, including research and development, production, and weaponization capabilities. Furthermore, there is considerable concern from the US regarding China's contact and sharing of chemical weapons expertise with other states of proliferation concern, including Syria and Iran.
As of December 2004, Israel has signed but not ratified the Chemical Weapons Convention, and according to the Russian Federation Foreign Intelligence Service, Israel has significant stores of chemical weapons of its own manufacture. It possesses a highly developed chemical and petrochemical industry, skilled specialists, and stocks of source material, and is capable of producing several nerve, blister and incapacitating agents. In 1974, in a hearing before the U.S. Senate Armed Services Committee, General Almquist stated that Israel had an offensive chemical weapons capability.
Chemical warfare from ancient to medieval times
Chemical weapons have been used for millennia in the form of poisoned arrows, but evidence can be found for the existence of more advanced forms of chemical weapons in ancient and classical times.
A good example of early chemical warfare was the late Stone Age (10 000 BC) hunter-gatherer societies in Southern Africa, known as the San. They used poisoned arrows, tipping the wood, bone and stone tips of their arrows with poisons obtained from their natural environment. These poisons were mainly derived from scorpion or snake venom, but it is believed that some poisonous plants were also utilized. The arrow was fired into the target of choice, usually an antelope (the favourite being an eland), with the hunter then tracking the doomed animal until the poison caused its collapse.
Dating from the 4th century BC, writings of the Mohist sect in China describe the use of bellows to pump smoke from burning balls of mustard and other toxic vegetables into tunnels being dug by a besieging army. Even older Chinese writings dating back to about 1000 BC contain hundreds of recipes for the production of poisonous or irritating smokes for use in war along with numerous accounts of their use. From these accounts we know of the arsenic-containing "soul-hunting fog", and the use of finely divided lime dispersed into the air to suppress a peasant revolt in AD 178.
The earliest recorded use of gas warfare in the West dates back to the 5th century BC, during the Peloponnesian War between Athens and Sparta. Spartan forces besieging an Athenian city placed a lighted mixture of wood, pitch, and sulfur under the walls hoping that the noxious smoke would incapacitate the Athenians, so that they would not be able to resist the assault that followed. Sparta wasn't alone in its use of unconventional tactics during these wars: Solon of Athens is said to have used hellebore roots to poison the water in an aqueduct leading from the Pleistrus River around 590 BC during the siege of Cirrha.
Chemical weapons were known and used in ancient and medieval China. Polish chronicler Jan Długosz mentions usage of posionous gas by Mongol army in 1241 in Battle of Legnica.
The rediscovery of chemical warfare
During the Renaissance, people again considered using chemical warfare. One of the earliest such references is from Leonardo da Vinci, who proposed a powder of sulfide of arsenic and verdigris in the 15th century:
throw poison in the form of powder upon galleys. Chalk, fine sulfide of arsenic, and powdered verdegris may be thrown among enemy ships by means of small mangonels, and all those who, as they breathe, inhale the powder into their lungs will become asphyxiated.
It is unknown whether this powder was ever actually used.
In the 17th century during sieges, armies attempted to start fires by launching incendiary shells filled with sulphur, tallow, rosin, turpentine, saltpeter, and/or antimony. Even when fires were not started, the resulting smoke and fumes provided a considerable distraction. Although their primary function was never abandoned, a variety of fills for shells were developed to maximize the effects of the smoke.
In 1672, during his siege of the city of Groningen, Christoph Bernhard van Galen (the Bishop of Münster) employed several different explosive and incendiary devices, some of which had a fill that included belladonna, intended to produce toxic fumes. Just three years later, August 27, 1675, the French and the Germans concluded the Strasbourg Agreement, which included an article banning the use of "perfidious and odious" toxic devices.
In 1854, Lyon Playfair, a British chemist, proposed a cacodyl cyanide artillery shell for use against enemy ships as way to solve the stalemate during the siege of Sevastopol. The proposal was backed by Admiral Thomas Cochrane of the Royal Navy. It was considered by the Prime Minister, Lord Palmerston, but the British Ordnance Department rejected the proposal as "as bad a mode of warfare as poisoning the wells of the enemy." Playfair’s response was used to justify chemical warfare into the next century:
There was no sense in this objection. It is considered a legitimate mode of warfare to fill shells with molten metal which scatters among the enemy, and produced the most frightful modes of death. Why a poisonous vapor which would kill men without suffering is to be considered illegitimate warfare is incomprehensible. War is destruction, and the more destructive it can be made with the least suffering the sooner will be ended that barbarous method of protecting national rights. No doubt in time chemistry will be used to lessen the suffering of combatants, and even of criminals condemned to death.
Later, during the American Civil War, New York school teacher John Doughty proposed the offensive use of chlorine gas, delivered by filling a 10 inch (254 millimeter) artillery shell with 2 to 3 quarts (2 to 3 liters) of liquid chlorine, which could produce many cubic feet (a few cubic meters) of chlorine gas. Doughty’s plan was apparently never acted on, as it was probably presented to Brigadier General James W. Ripley, Chief of Ordnance, who was described as being congenitally immune to new ideas.
A general concern over the use of poison gas manifested itself in 1899 at the Hague Conference with a proposal prohibiting shells filled with asphyxiating gas. The proposal was passed, despite a single dissenting vote from the United States. The American representative, Navy Captain Alfred Thayer Mahan, justified voting against the measure on the grounds that "the inventiveness of Americans should not be restricted in the development of new weapons."
Chemical warfare in World War I
The Germans were the first to use chemical weapons during the First World War, using tear gas. The first full-scale deployment of chemical weapon agents was during World War I, originating in the Second Battle of Ypres, April 22, 1915, when the Germans attacked French, Canadian and Algerian troops with chlorine gas. Deaths were light, though casualties relatively heavy. A total 50,965 tons of pulmonary, lachrymatory, and vesicant agents were deployed by both sides of the conflict, including chlorine, phosgene and mustard gas. Official figures declare about 1,176,500 non-fatal casualties and 85,000 fatalities directly caused by chemical weapon agents during the course of the war.
To this day unexploded WWI-era chemical ammunition is still frequently uncovered when the ground is dug in former battle or depot areas and continues to pose a threat to the civilian population in Belgium and France and less commonly in other countries. The French and Belgian governments have had to launch special programs for treating discovered ammunition.
After the war, most of the unused German chemical weapon agents were dropped into the Baltic Sea, a common disposal method among all the participants in several bodies of water. Over time, the salt water causes the shell casings to corrode, and mustard gas occasionally leaks from these containers and washes onto shore as a wax-like solid resembling ambergris. Even in this solidified form, the agent is active enough to cause severe contact burns to anybody handling it.
A soldier with mustard gas burns, ca. 1917-1918.
Chemical warfare in the interwar years
After World War I, the United States and many of the European powers attempted to take advantage of the opportunities that the war created by attempting to establish and hold colonies. During this interwar period, chemical agents were occasionally used to subdue populations and suppress rebellion.
Following the defeat of the Ottoman Empire in 1917, the Ottoman government collapsed completely, and the former empire was divided amongst the victorious powers in the Treaty of Sèvres. The British occupied Mesopotamia (present-day Iraq) and established a colonial government.
In 1920, the Arab and Kurdish people of Mesopotamia revolted against the British occupation, which cost the British dearly. As the Mesopotamian resistance gained strength, the British resorted to increasingly repressive measures, and Winston Churchill himself, in his role as Colonial Secretary, argued for the use of chemical agents, mostly mustard gas, on the Mesopotamian resistors. Mindful of the financial cost of suppressing the dissidents, Churchill was confident that chemical weapons could be inexpensively employed against the Mesopotamian tribes, saying "I do not understand this squeamishness about the use of gas. I am strongly in favour of using poison gas against uncivilised tribes."  Opposition to the use of gas and technical difficulties may have prevented the gas from being used in Mesopotamia (historians are currently divided on the issue). Chemical weapons had caused so much misery and revulsion in World War I that their use had become the ultimate atrocity in the minds of most people at the time. The newspapers, magazines and memoirs were filled with accounts of gas attacks. Much speculation was made about aerial bombardment of major cities with gas. In the 1920s generals reported that poison had never won a battle. The soldiers said they hated it and hated the gas masks. Only the chemists spoke out to say it was a good weapon. In 1925, sixteen of the world's major nations signed the Geneva Protocol, thereby pledging never to use gas in warfare again. Notably, in the United States, the Protocol languished in the Senate until 1975, when it was finally ratified.
During the Rif War in Spanish Morocco in 1921-1927, combined Spanish and French forces dropped mustard gas bombs in an attempt to put down the Berber rebellion. (See also: Rif, Abd el-Krim)
In 1935 Fascist Italy used mustard gas during the invasion of Ethiopia in the Second Italo-Abyssinian War. Ignoring the Geneva Protocol, which it signed seven years earlier, the Italian military dropped mustard gas in bombs, sprayed it from airplanes, and spread it in powdered form on the ground. 15,000 chemical casualties were reported, mostly from mustard gas.
Dressing the Wounded during a Gas Attack, a 1918 painting by the British war artist Austin Osman Spare.
Chemical warfare in World War II
During World War II, chemical warfare was revolutionized by Nazi Germany's accidental discovery of the nerve agents tabun and sarin by Gerhard Schrader, a chemist of IG Farben. The nerve agent soman was discovered by Nobel Prize laureate Richard Kuhn and his collaborator Konrad Henkel at the Kaiser Wilhelm Institute for Medical Research in Heidelberg in spring of 1944 (see Schmaltz 2005; Schmaltz 2006). The Nazis developed and manufactured large quantities of several agents, but chemical warfare was not extensively used by either side though chemical troops were set up (in Germany since 1934) and delivery technology was actively developed. Recovered Nazi documents suggest that German intelligence incorrectly thought that the Allies also knew of these compounds, interpreting their lack of mention in the Allies' scientific journals as evidence that information about them was being suppressed. Germany ultimately decided not to use the new nerve agents, fearing a potentially devastating Allied retaliatory nerve agent deployment.
William L. Shirer, in The Rise and Fall of the Third Reich, writes that the British high command considered the use of chemical weapons as a last-ditch defensive measure in the event of a Nazi invasion of Britain.
On the night of December 2, 1943, German Ju 88 bombers attacked the port of Bari in Southern Italy, sinking several American ships - among them John Harvey, which was carrying mustard gas intended for use in retaliation by the Allies if German forces initiated gas warfare. The presence of the gas was highly classified, and authorities ashore had no knowledge of it - which increased the number of fatalities, since physicians, who had no idea that they were dealing with the effects of mustard gas, prescribed treatment proper for those suffering from exposure and immersion.
The whole affair was kept secret at the time and for many years after the war (in the opinion of some, there was a deliberate and systematic cover-up). According to the U.S. military account, "Sixty-nine deaths were attributed in whole or in part to the mustard gas, most of them American merchant seamen" out of 628 mustard gas military casualties. The large number of civilian casualties among the Italian population were not recorded. Part of the confusion and controversy derives from the fact that the German attack was highly destructive and lethal in itself, also apart from the accidental additional effects of the gas (it was nicknamed "The Little Pearl Harbor"), and attribution of the causes of death between the gas and other causes is far from easy. The affair is the subject of two books: Disaster at Bari by Glenn B. Infield and Nightmare in Bari: The World War II Liberty Ship Poison Gas Disaster and Coverup by Gerald Reminick.
Although chemical weapons were not intentionally deployed on a large scale during on the front lines of the European Theatre of World War II, there were some recorded uses of them by the Axis Powers, when retaliation was not feared:
* The Japanese used mustard gas and the recently-developed blister agent Lewisite against Chinese troops and guerillas, including the Changde chemical weapon attack. During these attacks, the Japanese also employed biological warfare by intentionally spreading cholera, dysentery, typhoid, bubonic plague, and anthrax. Experiments involving chemical weapons were conducted on live prisoners (Unit 516). As of 2005, 60 years after the end of the war, canisters that were abandoned by Japan in their hasty retreat are still being dug up in construction sites, causing many injuries and deaths.
* In 1944, the Grand Mufti of Jerusalem, Amin al-Husayni, the senior Islamic religious authority of the Palestinian Arabs and close ally of Adolf Hitler, sponsored an unsuccessful chemical warfare assault on the Jewish community in Palestine. Five parachutists were supplied with maps of Tel Aviv, canisters of a German–manufactured "fine white powder," and instructions from the Mufti to dump chemicals into the Tel Aviv water system. District police commander Fayiz Bey Idrissi later recalled, "The laboratory report stated that each container held enough poison to kill 25,000 people, and there were at least ten containers."
* During the Holocaust, the Nazis used the insecticide Zyklon B, which contains hydrogen cyanide, to kill several million Jews and other peoples in extermination camps such as Auschwitz and Majdanek. Tear and reportedly poison gasses were used by against civilian and guerilla shelters during the Warsaw Ghetto Uprising in 1943, and again against sewer lines of communication during the Warsaw Uprising in 1944. In the concentration camp Struthof-Natzweiler in occupied Alsace the German physicians August Hirt and Otto Bickenbach conducted human experiments with mustard gas and phosgene on inmates to test possible prophylactic and therapeutic treatments causing injuries and death of many prisoners.
The chemical structure of Sarin nerve gas, discovered by Germany in 1938.
Chemical warfare during the Cold War
After World War II, the Allies recovered German artillery shells containing the three German nerve agents of the day (Tabun, Sarin, and Soman), prompting further research into nerve agents by all of the former Allies. Although the threat of global thermonuclear annihilation was foremost in the minds of most during the Cold War, both the Soviet and Western governments put enormous resources into developing chemical and biological weapons.
Developments by the Western governments
In 1952, researchers in Porton Down, England, invented the VX nerve agent but soon abandoned the project. In 1958 the British government traded their VX technology with the United States in exchange for information on thermonuclear weapons; by 1961 the U.S. was producing large amounts of VX and performing its own nerve agent research. This research produced at least three more agents; the four agents (VE, VG, VM, VX) are collectively known as the "V-Series" class of nerve agents.
Also in 1952 the U.S. Army patented a process for the "Preparation of Toxic Ricin", publishing a method of producing this powerful toxin.
During the 1960s, the U.S. explored the use of anticholinergic deleriant incapacitating agents. One of these agents, assigned the weapon designation BZ, was allegedly used experimentally in the Vietnam War. These allegations inspired the 1990 fictional film Jacob's Ladder.
Between 1967 and 1968, the U.S. decided to dispose of obsolete chemical weapons in an operation called Operation CHASE, which stood for "cut holes and sink 'em." Several shiploads of chemical and conventional weapons were put aboard old Liberty ships and sunk at sea.
In 1969, 23 U.S. servicemen and one U.S. civilian stationed in Okinawa, Japan, were exposed to low levels of the nerve agent sarin while repainting the depots' buildings. The weapons had been kept secret from Japan, sparking a furor in that country and an international incident. These munitions were moved in 1971 to Johnston Atoll under Operation Red Hat.
A UN working group began work on chemical disarmament in 1980. On April 4, 1984, U.S. President Ronald Reagan called for an international ban on chemical weapons. U.S. President George H.W. Bush and Soviet Union leader Mikhail Gorbachev signed a bilateral treaty on June 1, 1990, to end chemical weapon production and start destroying each of their nation's stockpiles. The multilateral Chemical Weapons Convention (CWC) was signed in 1993 and entered into force (EIF) in 1997.
On April 19, 1993 the FBI injected non-lethal CS grenades into wooden buildings during the Waco Siege. None of the Davidians left their building, however. CS is flammable and may have helped fuel the fires which later started. All the buildings within the site burned to the ground but few members tried to escape. Several of the bodies recovered after the raid had lethal doses of cyanide, a byproduct of burning CS.
United States Senate Report
A 1994 United States Senate Report, entitled "Is military research hazardous to veterans health? Lessons spanning a half century," detailed the United States' Department of Defense practice of experimenting on animal and human subjects, often without a latter's knowledge or consent.  This included:
* Approximately 60,000 [US] military personnel were used as human subjects in the 1940s to test the chemical agents mustard gas and lewisite. * Between the 1950s through the 1970s, at least 2,200 military personnel were subjected to various biological agents, referred to as Operation Whitecoat. Unlike most of the studies discussed in this report, Operation Whitecoat was truly voluntary. * Between 1951 and 1969, Dugway Proving Ground was the site of testing for various chemical and biological agents, including an open air aerodynamic dissemination test in 1968 that accidentally killed, on neighboring farms, approximately 6,400 sheep by an unspecified nerve agent.
Developments by the Soviet government
Due to the secrecy of the Soviet Union's government, very little information was available about the direction and progress of the Soviet chemical weapons until relatively recently. After the fall of the Soviet Union, Russian chemist Vil Mirzayanov published articles revealing illegal chemical weapons experimentation in Russia. In 1993, Mirzayanov was imprisoned and fired from his job at the State Research Institute of Organic Chemistry and Technology, where he had worked for 26 years. In March of 1994, after a major campaign by U.S. scientists on his behalf, Mirzayanov was released.
Among the information related by Vil Mirzayanov was the direction of Soviet research into the development of even more toxic nerve agents, which saw most of its success during the mid-1980s. Several highly toxic agents were developed during this period; the only unclassified information regarding these agents is that they are known in the open literature only as "Foliant" agents (named after the program under which they were developed) and by various code designations, such as A-230 and A-232.
According to Mirzayanov, the Soviets also developed agents that were safer to handle, leading to the development of the so-called binary weapons, in which precursors for the nerve agents are mixed in a munition to produce the agent just prior to its use. Because the precursors are generally significantly less hazardous than the agents themselves, this technique makes handling and transporting the munitions a great deal simpler. Additionally, precursors to the agents are usually much easier to stabilize than the agents themselves, so this technique also made it possible to increase the shelf life of the agents a great deal. During the 1980s and 1990s, binary versions of several Soviet agents were developed and are designated as "Novichok" agents (after the Russian word for "newcomer").
Chemical warfare in the Iran-Iraq War
in 1988. Then held by Iranian troops and Iraqi Kurdish guerrillas allied with Tehran. According to Iraqi documents, assistance in developing chemical weapons was obtained from firms in many countries, including the United States, West Germany, the United Kingdom, France and China. ]] The Iran-Iraq War began in 1980 when Iraq attacked Iran. Early in the conflict, Iraq began to employ mustard gas and tabun delivered by bombs dropped from airplanes; approximately 5% of all Iranian casualties are directly attributable to the use of these agents. Iraq and the U.S. government alleged that Iran was also using chemical weapons, but independent sources were unable to confirm these allegations.
About 100,000 Iranian soldiers were victims of Iraq's chemical attacks. Many were hit by mustard gas. The official estimate does not include the civilian population contaminated in bordering towns or the children and relatives of veterans, many of whom have developed blood, lung and skin complications, according to the Organization for Veterans. Nerve gas agents killed about 20,000 Iranian soldiers immediately, according to official reports. Of the 80,000 survivors, some 5,000 seek medical treatment regularly and about 1,000 are still hospitalized with severe, chronic conditions.  Iraq also targeted Iranian civilians with chemical weapons. Many thousands were killed in attacks on populations in villages and towns, as well as front-line hospitals. Many still suffer from the severe effects.
Despite the removal of Saddam and his regime by Coalition forces, there is deep resentment and anger in Iran that it was Western companies based in West Germany, France, and the U.S. that helped Iraq develop its chemical weapons arsenal in the first place, and that the world did nothing to punish Iraq for its use of chemical weapons throughout the war.
Shortly before war ended in 1988, the Iraqi Kurdish village of Halabja was exposed to multiple chemical agents, killing about 5,000 of the town's 50,000 residents. After the incident, traces of mustard gas and the nerve agents sarin, tabun and VX were discovered. While it appears that Iraqi government forces are to blame, some debate continues over the question of whether Iraq was really the responsible party, and whether this was a deliberate or accidental act. (see Halabja poison gas attack)
During the Persian Gulf War in 1991, Coalition forces began a ground war in Iraq. Despite the fact that they did possess chemical weapons, Iraq did not use any chemical agents against coalition forces. The commander of the Allied Forces, Gen. H. Norman Schwarzkopf, suggested this may have been due to Iraqi fear of retaliation with nuclear weapons.
Chemical warfare in the Falklands War
Technically, the employment of tear gas by Argentine forces during the 1982 invasion of the Falkland Islands constitutes chemical warfare. However, the tear gas grenades were employed as nonlethal weapons to avoid British casualties. (In the hope that Britain would more easily accept the loss of territory in the conflict) The barrack buildings the weapons were used on proved to be deserted in any case.
Chemical weapons and terrorism
organizations, chemical weapons might be considered an ideal choice for a mode of attack, if they are available: they are cheap, relatively accessible, and easy to transport. A skilled chemist can readily synthesize most chemical agents if the precursors are available.
Some political commentators dispute the practicality of chemical and biological weapons as tools of terrorism, however, stating that the effective use of such weapons is much more difficult than the use of conventional explosives, and that they are more useful in the fear that they generate. 
The earliest successful use of chemical agents in a non-combat setting was in 1946, motivated by a desire to obtain revenge on Germans for the Holocaust. Three members of a Jewish group calling themselves Dahm Y'Israel Nokeam ("Avenging Israel's Blood") hid in a bakery in the Stalag 13 prison camp near Nuremberg, Germany, where several thousand SS troops were being detained. The three applied an arsenic-containing mixture to loaves of bread, sickening more than 2,000 prisoners, of whom more than 200 required hospitalization.
In July of 1974, a group calling themselves the Aliens of America successfully firebombed the houses of a judge, two police commissioners, and one of the commissioner’s cars, burned down two apartment buildings, and bombed the Pan Am Terminal at Los Angeles International Airport, killing three people and injuring eight. The organization, which turned out to be a single resident alien named Muharem Kurbegovic, claimed to have developed and possessed a supply of sarin, as well as 4 unique nerve agents named AA1, AA2, AA3, and AA4S. Although no agents were found at the time he was arrested in August of 1974, he had reportedly acquired "all but one" of the ingredients required to produce a nerve agent. A search of his apartment turned up a variety of materials, including precursors for phosgene and a drum containing 25 pounds of sodium cyanide.
The first successful use of chemical agents by terrorists against a general civilian population was on March 20, 1995. Aum Shinrikyo, an apocalyptic group based in Japan that believed it necessary to destroy the planet, released sarin into the Tokyo subway system killing 12 and injuring over 5,000. The group had attempted biological and chemical attacks on at least 10 prior occasions, but managed to affect only cult members. The group did manage to successfully release sarin outside an apartment building in Matsumoto in June 1994; this use was directed at a few specific individuals living in the building and was not an attack on the general population.
In 2001, after carrying out the attacks in New York City on September 11, the organization Al Qaeda announced that they were attempting to acquire radiological, biological and chemical weapons. This threat was lent a great deal of credibility when a large archive of videotapes was obtained by the cable television network CNN in August of 2002 showing, among other things, the killing of three dogs by an apparent nerve agent.
On October 26, 2002, Russian special forces used KOLOKOL-1, an aerosolized fentanyl derivative, as a precursor to an assault on Chechen terrorists, ending the Moscow theater hostage crisis. All 42 of the terrorists and 120 of the hostages were killed during the raid; all but one of hostages killed died from the effects of the agent.
A nuclear weapon is a weapon which derives its destructive force from nuclear reactions of fission or fusion. As a result, even a nuclear weapon with a small yield is significantly more powerful than the largest conventional explosives, and a single weapon is capable of destroying an entire city.
In the history of warfare, nuclear weapons have been used only twice, both during the closing days of World War II. The first event occurred on the morning of August 6, 1945, when the United States dropped a uranium gun-type device code-named "Little Boy" on the Japanese city of Hiroshima. The second event occurred three days later when the United States dropped a plutonium implosion-type device code-named "Fat Man" on the city of Nagasaki. The use of these weapons, which resulted in the immediate deaths of around 100,000 to 200,000 people and even more over time, was and remains controversial — critics around the world charged that they were unnecessary acts of mass killing, while others claimed that they ultimately reduced casualties on both sides by hastening the end of the war (see Atomic bombings of Hiroshima and Nagasaki for a full discussion).
Since the Hiroshima and Nagasaki bombings, nuclear weapons have been detonated on over two thousand occasions for testing and demonstration purposes. The only countries known to have detonated such weapons are (chronologically) the United States, Soviet Union, United Kingdom, France, People's Republic of China, India, Pakistan, and North Korea.
Various other countries may hold nuclear weapons but have never publicly admitted possession, or their claims to possession have not been verified. For example, Israel has modern airborne delivery systems and appears to have an extensive nuclear program with hundreds of warheads (see Israel and weapons of mass destruction), though it officially maintains a policy of "ambiguity" with respect to its actual possession of nuclear weapons. In an apparent slip, Israel's Prime Minister Ehud Olmert admitted in an interview that Israel was among the countries that possessed nuclear weapons. According to some estimates, it possesses as many as 200 nuclear warheads. Iran currently stands accused by a number of governments of attempting to develop nuclear capabilities, though its government claims that its acknowledged nuclear activities, such as uranium enrichment, are for peaceful purposes. South Africa also secretly developed a small nuclear arsenal, but disassembled it in the early 1990s. (For more information see List of states with nuclear weapons.)
Apart from their use as weapons, nuclear explosives have been tested and used for various non-military uses.Synthetic elements such as Einsteinium , created by nuclear fission, were discovered in the aftermath of the first hydrogen bomb test.
The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 kilometers (11 mi) above the hypocenter.
The first nuclear weapons were created in the United States by an international team, including many displaced scientists from central Europe, with assistance from the United Kingdom and Canada during World War II as part of the top-secret Manhattan Project. While the first weapons were developed primarily out of fear that Nazi Germany would develop them first, they were eventually used against the Japanese cities of Hiroshima and Nagasaki in August 1945. The Soviet Union developed and tested their first nuclear weapon in 1949, based partially on information obtained from Soviet espionage in the United States. Both the U.S. and USSR would go on to develop weapons powered by nuclear fusion (hydrogen bombs) by the mid-1950s. With the invention of reliable rocketry during the 1960s, it became possible for nuclear weapons to be delivered anywhere in the world on a very short notice, and the two Cold War superpowers adopted a strategy of deterrence to maintain a shaky peace.
The aftermath of the atomic bombing of Hiroshima.
U.S. and USSR/Russian nuclear weapons stockpiles, 1945-2006.
Nuclear weapons were symbols of military and national power, and nuclear testing was often used both to test new designs as well as to send political messages. Other nations also developed nuclear weapons during this time, including the United Kingdom, France, and China. These five members of the "nuclear club" agreed to attempt to limit the spread of nuclear proliferation to other nations, though four other countries (India, South Africa, Pakistan, and Israel) developed nuclear arms during this time. At the end of the Cold War in the early 1990s, the Russian Federation inherited the weapons of the former USSR, and along with the U.S., pledged to reduce their stockpile for increased international safety. Nuclear proliferation has continued, though, with Pakistan testing their first weapons in 1998, and North Korea performing a test in 2006. In January 2005, Pakistani metallurgist Abdul Qadeer Khan confessed to selling nuclear technology and information of nuclear weapons to Iran, Libya, and North Korea in a massive, international proliferation ring. On October 9, 2006, North Korea claimed it had conducted an underground nuclear test, though the very small apparent yield of the blast has led many to conclude that it was not fully successful (see 2006 North Korean nuclear test).
Nuclear weapons have been at the heart of many national and international political disputes and have played a major part in popular culture since their dramatic public debut in the 1940s and have usually symbolized the ultimate ability of mankind to utilize the strength of nature for destruction.
There have been (at least) four major false alarms, the most recent in 1995, that almost resulted in the U.S. or USSR/Russia launching its weapons in retaliation for a supposed attack. Additionally, during the Cold War the U.S. and USSR came close to nuclear warfare several times, most notably during the Cuban Missile Crisis. As of 2005, there are estimated to be at least 29,000 nuclear weapons held by at least eight countries, 96 percent of them in the possession of the United States and Russia.
Types of nuclear weapons
There are two basic types of nuclear weapons. The first are weapons which produce their explosive energy through nuclear fission reactions alone. These are known colloquially as atomic bombs, A-bombs, or fission bombs. In fission weapons, a mass of fissile material (enriched uranium or plutonium) is assembled into a supercritical mass—the amount of material needed to start an exponentially growing nuclear chain reaction—either by shooting one piece of subcritical material into another, or by compressing a subcritical mass with chemical explosives, at which point neutrons are injected and the reaction begins. A major challenge in all nuclear weapon designs is ensuring that a significant fraction of the fuel is consumed before the weapon destroys itself. The amount of energy released by fission bombs can range between the equivalent of less than a ton of TNT upwards to around 500,000 tons (500 kilotons) of TNT.
The second basic type of nuclear weapon produces a large amount of its energy through nuclear fusion reactions, and can be over a thousand times more powerful than fission bombs. These are known as hydrogen bombs, H-bombs, thermonuclear bombs, or fusion bombs. Only six countries— United States, Russia, United Kingdom, People's Republic of China, France, and India—have detonated, or have attempted to detonate, hydrogen bombs. Hydrogen bombs work by utilizing the Teller-Ulam design, in which a fission bomb is detonated in a specially manufactured compartment adjacent to a fusion fuel. The gamma and X-rays of the fission explosion compress and heat a capsule of tritium, deuterium, or lithium deuteride starting a fusion reaction. Neutrons emitted by this fusion reaction can induce a final fission stage in a depleted uranium tamper surrounding the fusion fuel, increasing the yield considerably as well as the amount of nuclear fallout. Each of these components is known as a "stage", with the fission bomb as the "primary" and the fusion capsule as the "secondary". By chaining together numerous stages with increasing amounts of fusion fuel, thermonuclear weapons can be made to an almost arbitrary yield; the largest ever detonated (the Tsar Bomba of the USSR) released an energy equivalent to over 50 million tons (megatons) of TNT, though most modern weapons are nowhere near that large.
There are other types of nuclear weapons as well. For example, a boosted fission weapon is a fission bomb which increases its explosive yield through a small amount of fusion reactions, but it is not a hydrogen bomb. Some weapons are designed for special purposes; a neutron bomb is a nuclear weapon that yields a relatively small explosion but a relatively large amount of prompt radiation; such a device could theoretically be used to cause massive casualties while leaving infrastructure mostly intact. The detonation of a nuclear weapon is accompanied by a blast of neutron radiation. Surrounding a nuclear weapon with suitable materials (such as cobalt or gold) creates a weapon known as a salted bomb. This device can produce exceptionally large quantities of radioactive contamination. Most variety in nuclear weapon design is in different yields of nuclear weapons for different types of purposes, and in manipulating design elements to attempt to make weapons extremely small.
The two basic fission weapon designs.
Nuclear warfare strategy is a way for either fighting or avoiding a nuclear war. The policy of trying to ward off a potential attack by a nuclear weapon from another country by threatening nuclear retaliation is known as the strategy of nuclear deterrence. The goal in deterrence is to always maintain a second strike status (the ability of a country to respond to a nuclear attack with one of its own) and potentially to strive for first strike status (the ability to completely destroy an enemy's nuclear forces before they could retaliate). During the Cold War, policy and military theorists in nuclear-enabled countries worked out models of what sorts of policies could prevent one from ever being attacked by a nuclear weapon.
Different forms of nuclear weapons delivery (see below) allow for different types of nuclear strategy, primarily by making it difficult to defend against them and difficult to launch a pre-emptive strike against them. Sometimes this has meant keeping the weapon locations hidden, such as putting them on submarines or train cars whose locations are very hard for an enemy to track, and other times this means burying them in hardened bunkers. Other responses have included attempts to make it seem likely that the country could survive a nuclear attack, by using missile defense (to destroy the missiles before they land) or by means of civil defense (using early warning systems to evacuate citizens to a safe area before an attack). Note that weapons which are designed to threaten large populations or to generally deter attacks are known as "strategic" weapons. Weapons which are designed to actually be used on a battlefield in military situations are known as "tactical" weapons.
There are critics of the very idea of "nuclear strategy" for waging nuclear war who have suggested that a nuclear war between two nuclear powers would result in mutual annihilation. From this point of view, the significance of nuclear weapons is purely to deter war because any nuclear war would immediately escalate out of mutual distrust and fear, resulting in mutual assured destruction. This threat of national, if not global, destruction has been a strong motivation for anti-nuclear weapons activism.
Critics from the peace movement and within the military establishment have questioned the usefulness of such weapons in the current military climate. The use of (or threat of use of) such weapons would generally be contrary to the rules of international law applicable in armed conflict, according to an Advisory opinion issued by the International Court of Justice in 1996.
Perhaps the most controversial idea in nuclear strategy is that nuclear proliferation would be desirable. This view argues that unlike conventional weapons nuclear weapons successfully deter all-out war between states, as they did during the Cold War between the U.S. and the Soviet Union. Political scientist Kenneth Waltz is the most prominent advocate of this argument.
The United States' Peacekeeper missile was a MIRVed delivery system. Each missile could contain up to ten nuclear warheads (shown in red), each of which could be aimed at a different target. These were developed to make missile defense very difficult for an enemy country.
Nuclear weapons delivery—the technology and systems used to bring a nuclear weapon to its target—is an important aspect of nuclear weapons relating both to nuclear weapon design and nuclear strategy.
Historically the first method of delivery, and the method used in the two nuclear weapons actually used in warfare, is as a gravity bomb, dropped from bomber aircraft. This method is usually the first developed by countries as it does not place many restrictions on the size of the weapon, and weapon miniaturization is something which requires considerable weapons design knowledge. It does, however, limit the range of attack, the response time to an impending attack, and the number of weapons which can be fielded at any given time. Additionally, specialized delivery systems are usually not necessary; especially with the advent of miniaturization, nuclear bombs can be delivered by both strategic bombers and tactical fighter-bombers, allowing an air force to use its current fleet with little or no modification. This method may still be considered the primary means of nuclear weapons delivery; the majority of U.S. nuclear warheads, for example, are represented in free-fall gravity bombs, namely the B61.
More preferable from a strategic point of view are nuclear weapons mounted onto a missile, which can use a ballistic trajectory to deliver a warhead over the horizon. While even short range missiles allow for a faster and less vulnerable attack, the development of intercontinental ballistic missiles (ICBMs) and submarine-launched ballistic missiles (SLBMs) has allowed some nations to plausibly deliver missiles anywhere on the globe with a high likelihood of success. More advanced systems, such as multiple independently targetable reentry vehicles (MIRVs) allow multiple warheads to be launched at several targets from any one missile, reducing the chance of any successful missile defense. Today, missiles are most common among systems designed for delivery of nuclear weapons. Making a warhead small enough to fit onto a missile, though, can be a difficult task.
Tactical weapons (see above) have involved the most variety of delivery types, including not only gravity bombs and missiles but also artillery shells, land mines, and nuclear depth charges and torpedoes for anti-submarine warfare. An atomic mortar was also tested at one time by the United States. Small, two-man portable tactical weapons (somewhat misleadingly referred to as suitcase bombs), such as the Special Atomic Demolition Munition, have been developed, although the difficulty to combine sufficient yield with portability limits their military utility.
The first nuclear weapons were gravity bombs, such as the "Fat Man" weapon dropped on Nagasaki, Japan. These weapons were very large and could only be delivered by a bomber aircraft.
Governance and control
Because of the immense military power they can confer, the political control of nuclear weapons has been a key issue for as long as they have existed. In the late 1940s, lack of mutual trust prohibited the United States and the Soviet Union from making ground towards international arms control agreements, but by the 1960s steps were being taken to limit both the proliferation of nuclear weapons to other countries and the environmental effects of nuclear testing. The Partial Test Ban Treaty (1963) restricted all nuclear testing to underground nuclear testing, to prevent contamination from nuclear fallout, while the Nuclear Non-Proliferation Treaty (1968) attempted to place restrictions on the types of activities which signatories could participate in, with the goal of allowing the transference of non-military nuclear technology to member countries without fear of proliferation. In 1957, the International Atomic Energy Agency (IAEA) was established under the mandate of the United Nations in order to encourage the development of the peaceful applications of nuclear technology, provide international safeguards against its misuse, and facilitate the application of safety measures in its use. In 1996, many nations signed and ratified the Comprehensive Test Ban Treaty which prohibits all testing of nuclear weapons, which would impose a significant hindrance to their development by any complying country.
Additional treaties have governed nuclear weapons stockpiles between individual countries, such as the SALT I and START I treaties, which limited the numbers and types of nuclear weapons between the United States and the U.S.S.R.
Nuclear weapons have also been opposed by agreements between countries. Many nations have been declared Nuclear-Weapon-Free Zones, areas where nuclear weapons production and deployment are prohbited, through the use of treaties. The Treaty of Tlatelolco (1967) prohibited any production or deployment of nuclear weapons in Latin America and the Caribbean, and the Treaty of Pelindaba (1964) prohibits nuclear weapons in many African countries. As recently as 2006 a Central Asian Nuclear Weapon Free Zone was established amongst the former Soviet republics of Central Asia prohibiting nuclear weapons.
In 1996, the International Court of Justice, the highest court of the United Nations, issued an Advisory Opinion concerned with the "Legality of the Threat or Use of Nuclear Weapons". The court ruled that the use or threat of use of nuclear weapons would violate various articles of international law, including the Geneva Conventions, the Hague Conventions, the UN Charter, and the Universal Declaration of Human Rights.
The International Atomic Energy Agency was created in 1957 in order to encourage the peaceful development of nuclear technology while providing international safeguards against nuclear proliferation.
A radiological weapon (or radiological dispersion device, RDD) is any weapon that is designed to spread radioactive material with the intent to kill, and cause disruption psychologically and financially by impacting a city. One possible way of dispersing the material is by using a “dirty bomb,” a conventional explosive which disperses radioactive material. Dirty bombs are not a type of nuclear weapon, which requires a nuclear chain reaction and the creation of a critical mass. Whereas a nuclear weapon will usually create mass casualties immediately following the blast, a dirty bomb scenario would initially cause only minimal casualties from the conventional explosion.
Radiological weapons have been suggested as a possible weapon of terrorism used to create panic and casualties in densely populated areas. They could also render a great deal of property useless for an extended period, unless costly remediation was undertaken. The radiological source greatly impacts the effectiveness of a radiological weapon. Factors such as: energy and type of radiation, half-life, size of explosion, availability, shielding, portablity, and the role of the environment will determine the effect of the radiological weapon. Radioisotopes that pose the greatest security risk include: 137Cs, used in radiological medical equipment, 60Co, 241Am, 252Cf, 192Ir, 238Pu, 90Sr, and 226Ra. All of these isotopes, except for the latter, are created in nuclear power plants. While the amount of radiation dispersed from the event will likely be minimal, the fact of any radiation may be enough to cause panic and disruption.
Radiological weapons are widely considered to be militarily useless for a state-sponsored army and are not believed to have been deployed by any military forces. Firstly, the use of such a weapon is of no use to an occupying force, as the target area becomes uninhabitable. Furthermore, area-denial weapons are generally of limited use to an attacking army, as it slows the rate of advance. Finally, like biological weapons, radiological weapons can take days to act on the opposing force. They therefore not only fail in neutralizing the opposing force instantly, but they also allow time for massive retaliation.
Means of radiological warfare that do not rely on any specific weapon, but rather on spreading radioactive contamination via a food chain or water table, seem to be more effective in some ways, but share many of the same problems as chemical warfare.
Iraq under Saddam Hussein is reported to have tested a radiological weapon in 1987 for use against Iran. This weapon was found to be impractical because the radioactive isotopes in the weapon would decay quickly, rendering it useless within a week after the weapon was manufactured. Furthermore, it was found that for the radioactive material to spread, weather conditions had to be ideal. These problems are in general shared by all forms of air-borne radiological warfare.
There is currently (as of 2006) an ongoing debate about the damage that terrorists using such a weapon might inflict. Many experts believe that such a bomb would be unlikely to harm more than a few people and hence it would be no more deadly than a conventional bomb. Hence, this line of argument goes, the objectively dominant effect would be the moral and economic damage due to the massive fear and panic such an incident would spur. On the other hand, some believe that the fatalities and injuries might be in fact much more severe. This point is, e.g., made by physicists Paul Zimmerman et al. (King's College London) who reexamined the Goiânia accident which is arguably comparable. (Ref.: Nature Science Update of 5 May 2004)
The history of radioactive weaponry may be traced to a 1943 memo to Brigadier General Leslie Groves of the Manhattan Project. Transmitting a report entitled, "Use of Radioactive Materials as a Military Weapon," the memo states:
As a gas warfare instrument the material would ... be inhaled by personnel. The amount necessary to cause death to a person inhaling the material is extremely small. It has been estimated that one millionth of a gram accumulating in a person's body would be fatal. There are no known methods of treatment for such a casualty.... It cannot be detected by the senses; It can be distributed in a dust or smoke form so finely powdered that it will permeate a standard gas mask filter in quantities large enough to be extremely damaging....
Radioactive warfare can be used ... To make evacuated areas uninhabitable; To contaminate small critical areas such as rail-road yards and airports; As a radioactive poison gas to create casualties among troops; Against large cities, to promote panic, and create casualties among civilian populations.
Areas so contaminated by radioactive dusts and smokes, would be dangerous as long as a high enough concentration of material could be maintained.... they can be stirred up as a fine dust from the terrain by winds, movement of vehicles or troops, etc., and would remain a potential hazard for a long time.
These materials may also be so disposed as to be taken into the body by ingestion instead of inhalation. Reservoirs or wells would be contaminated or food poisoned with an effect similar to that resulting from inhalation of dust or smoke. Four days production could contaminate a million gallons of water to an extent that a quart drunk in one day would probably result in complete incapacitation or death in about a month's time.
Poslednji odgovor u temi napisan je pre više od 6 meseci.
Temu ne bi trebalo "iskopavati" osim u slučaju da imate nešto važno da dodate. Ako ipak želite napisati komentar, kliknite na dugme "Odgovori" u meniju iznad ove poruke. Postoje teme kod kojih su odgovori dobrodošli bez obzira na to koliko je vremena od prošlog prošlo. Npr. teme o određenom piscu, knjizi, muzičaru, glumcu i sl. Nemojte da vas ovaj spisak ograničava, ali nemojte ni pisati na teme koje su završena priča.