94-594: The W93 is an American nuclear warhead planned to replace the W76 and W88 warheads on United States Navy submarines from 2034. The warhead will be carried on the new Columbia-class submarines and will use a new aeroshell, the Mark 7 reentry body (RB). The warhead will be designed by Los Alamos National Laboratory . The Mark 7 RB will also be used to house the United Kingdom 's new warhead, designed in parallel to
188-513: A misnomer , as their energy comes from the nucleus of the atom, just as it does with fusion weapons. In fission weapons, a mass of fissile material ( enriched uranium or plutonium ) is forced into supercriticality —allowing an exponential growth of nuclear chain reactions —either by shooting one piece of sub-critical material into another (the "gun" method) or by compression of a sub-critical sphere or cylinder of fissile material using chemically fueled explosive lenses . The latter approach,
282-665: A policy of deliberate ambiguity , it does not acknowledge having them. Germany , Italy , Turkey , Belgium , the Netherlands , and Belarus are nuclear weapons sharing states. South Africa is the only country to have independently developed and then renounced and dismantled its nuclear weapons. The Treaty on the Non-Proliferation of Nuclear Weapons aims to reduce the spread of nuclear weapons, but there are different views of its effectiveness. There are two basic types of nuclear weapons: those that derive
376-696: A conference—called for in the manifesto—in Pugwash, Nova Scotia , Eaton's birthplace. This conference was to be the first of the Pugwash Conferences on Science and World Affairs , held in July 1957. By the 1960s, steps were taken to limit both the proliferation of nuclear weapons to other countries and the environmental effects of nuclear testing . The Partial Nuclear Test Ban Treaty (1963) restricted all nuclear testing to underground nuclear testing , to prevent contamination from nuclear fallout, whereas
470-458: A faster and less vulnerable attack, the development of long-range intercontinental ballistic missiles (ICBMs) and submarine-launched ballistic missiles (SLBMs) has given some nations the ability 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), can launch multiple warheads at different targets from one missile, reducing
564-551: A few nations possess such weapons or are suspected of seeking them. The only countries known to have detonated nuclear weapons—and acknowledge possessing them—are (chronologically by date of first test) the United States , the Soviet Union (succeeded as a nuclear power by Russia ), the United Kingdom , France , China , India , Pakistan , and North Korea . Israel is believed to possess nuclear weapons, though, in
658-555: A fission bomb to initiate them. Such a device might provide a simpler path to thermonuclear weapons than one that required the development of fission weapons first, and pure fusion weapons would create significantly less nuclear fallout than other thermonuclear weapons because they would not disperse fission products. In 1998, the United States Department of Energy divulged that the United States had, "...made
752-421: A fusion weapon as of January 2016 , though this claim is disputed. Thermonuclear weapons are considered much more difficult to successfully design and execute than primitive fission weapons. Almost all of the nuclear weapons deployed today use the thermonuclear design because it results in an explosion hundreds of times stronger than that of a fission bomb of similar weight. Thermonuclear bombs work by using
846-472: A nation's economic electronics-based infrastructure. Because the effect is most effectively produced by high altitude nuclear detonations (by military weapons delivered by air, though ground bursts also produce EMP effects over a localized area), it can produce damage to electronics over a wide, even continental, geographical area. Research has been done into the possibility of pure fusion bombs : nuclear weapons that consist of fusion reactions without requiring
940-537: A new nuclear strategy, one that is distinct from that which gave relative stability during the Cold War. Since 1996, the United States has had a policy of allowing the targeting of its nuclear weapons at terrorists armed with weapons of mass destruction . Robert Gallucci argues that although traditional deterrence is not an effective approach toward terrorist groups bent on causing a nuclear catastrophe, Gallucci believes that "the United States should instead consider
1034-425: A nuclear war between two nations would result in mutual annihilation. From this point of view, the significance of nuclear weapons is to deter war because any nuclear war would escalate out of mutual distrust and fear, resulting in mutually 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
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#17327807179071128-411: 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 capability (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 destroy an enemy's nuclear forces before they could retaliate). During
1222-465: A nuclear weapon is a gravity bomb dropped from aircraft ; this was the method used by the United States against Japan in 1945. This method places few restrictions on the size of the weapon. It does, however, limit attack range, response time to an impending attack, and the number of weapons that a country can field at the same time. With miniaturization, nuclear bombs can be delivered by both strategic bombers and tactical fighter-bombers . This method
1316-409: A nuclear weapon to its target is an important factor affecting both nuclear weapon design and nuclear strategy . The design, development, and maintenance of delivery systems are among the most expensive parts of a nuclear weapons program; they account, for example, for 57% of the financial resources spent by the United States on nuclear weapons projects since 1940. The simplest method for delivering
1410-433: 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 long-lived radioactive contamination . It has been conjectured that such a device could serve as a "doomsday weapon" because such a large quantity of radioactivities with half-lives of decades, lifted into the stratosphere where winds would distribute it around
1504-421: A policy of expanded deterrence, which focuses not solely on the would-be nuclear terrorists but on those states that may deliberately transfer or inadvertently leak nuclear weapons and materials to them. By threatening retaliation against those states, the United States may be able to deter that which it cannot physically prevent.". Graham Allison makes a similar case, arguing that the key to expanded deterrence
1598-447: A significant portion of their energy from fission reactions used to "trigger" fusion reactions, and fusion reactions can themselves trigger additional fission reactions. Only six countries—the United States , Russia , the United Kingdom , China , France , and India —have conducted thermonuclear weapon tests. Whether India has detonated a "true" multi-staged thermonuclear weapon is controversial. North Korea claims to have tested
1692-486: A strategic nuclear bomber fleet. The bomber force consists of 51 nuclear-armed B-52 Stratofortresses , and 20 B-2 Spirits . All 64 B-1s were retrofitted to operate in a solely conventional mode by 2007 and thus don't count as nuclear platforms. In addition to this, the U.S. military can also deploy smaller tactical nuclear weapons either through cruise missiles or with conventional fighter-bombers . The U.S. maintains about 400 nuclear gravity bombs capable of use by
1786-550: A substantial investment" in the past to develop pure fusion weapons, but that, "The U.S. does not have and is not developing a pure fusion weapon", and that, "No credible design for a pure fusion weapon resulted from the DOE investment". Nuclear isomers provide a possible pathway to fissionless fusion bombs. These are naturally occurring isotopes ( Hf being a prominent example) which exist in an elevated energy state. Mechanisms to release this energy as bursts of gamma radiation (as in
1880-507: A test. ) The U.S. also investigated a wide range of possible nonlethal, psychobehavioral chemical incapacitating agents including psychedelic indoles such as LSD and marijuana derivatives, as well as several glycolate anticholinergics. One of the anticholinergic compounds, 3-quinuclidinyl benzilate , was assigned the NATO code BZ and was weaponized at the beginning of the 1960s for possible battlefield use. Alleged use of chemical agents by
1974-420: Is a thermonuclear weapon that yields a relatively small explosion but a relatively large amount of neutron radiation . Such a weapon could, according to tacticians, be used to cause massive biological casualties while leaving inanimate infrastructure mostly intact and creating minimal fallout. Because high energy neutrons are capable of penetrating dense matter, such as tank armor, neutron warheads were procured in
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#17327807179072068-721: Is an explosive device that derives its destructive force from nuclear reactions , either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb ), producing a nuclear explosion . Both bomb types release large quantities of energy from relatively small amounts of matter . The first test of a fission ("atomic") bomb released an amount of energy approximately equal to 20,000 tons of TNT (84 TJ ). The first thermonuclear ("hydrogen") bomb test released energy approximately equal to 10 million tons of TNT (42 PJ). Nuclear bombs have had yields between 10 tons TNT (the W54 ) and 50 megatons for
2162-456: Is analogous to identifying a criminal by fingerprints. "The goal would be twofold: first, to deter leaders of nuclear states from selling weapons to terrorists by holding them accountable for any use of their weapons; second, to give leaders every incentive to tightly secure their nuclear weapons and materials." According to the Pentagon's June 2019 " Doctrine for Joint Nuclear Operations " of
2256-403: Is coming up with ways of tracing nuclear material to the country that forged the fissile material. "After a nuclear bomb detonates, nuclear forensics cops would collect debris samples and send them to a laboratory for radiological analysis. By identifying unique attributes of the fissile material, including its impurities and contaminants, one could trace the path back to its origin." The process
2350-481: Is for the purpose of achieving different yields for different situations , and in manipulating design elements to attempt to minimize weapon size, radiation hardness or requirements for special materials, especially fissile fuel or tritium. Some nuclear weapons are designed for special purposes; most of these are for non-strategic (decisively war-winning) purposes and are referred to as tactical nuclear weapons . The neutron bomb purportedly conceived by Sam Cohen
2444-528: Is known for using civilian populations to test the effects of bioweapons. In 1950, the US Navy conducted a secret experiment on the civilian population of the San Francisco Bay Area during operation Operation Sea-Spray , in which over 800,000 residents were unknowingly sprayed with pathogens. This led to at least one death and claims that the ecology had been changed irreversibly. In 1951,
2538-503: Is no evidence that it is feasible beyond the military domain. However, the U.S. Air Force funded studies of the physics of antimatter in the Cold War , and began considering its possible use in weapons, not just as a trigger, but as the explosive itself. A fourth generation nuclear weapon design is related to, and relies upon, the same principle as antimatter-catalyzed nuclear pulse propulsion . Most variation in nuclear weapon design
2632-409: Is not a fusion bomb. In the boosted bomb, the neutrons produced by the fusion reactions serve primarily to increase the efficiency of the fission bomb. There are two types of boosted fission bomb: internally boosted, in which a deuterium-tritium mixture is injected into the bomb core, and externally boosted, in which concentric shells of lithium-deuteride and depleted uranium are layered on the outside of
2726-490: Is not clear that this has ever been implemented, and their plausible use in nuclear weapons is a matter of dispute. The other basic type of nuclear weapon produces a large proportion of its energy in nuclear fusion reactions. Such fusion weapons are generally referred to as thermonuclear weapons or more colloquially as hydrogen bombs (abbreviated as H-bombs ), as they rely on fusion reactions between isotopes of hydrogen ( deuterium and tritium ). All such weapons derive
2820-454: Is the primary means of nuclear weapons delivery; the majority of U.S. nuclear warheads, for example, are free-fall gravity bombs, namely the B61 , which is being improved upon to this day. Preferable from a strategic point of view is a nuclear weapon mounted on a missile , which can use a ballistic trajectory to deliver the warhead over the horizon. Although even short-range missiles allow for
2914-530: Is unclear because some tests involved multiple devices while a few failed to explode or were designed not to create a nuclear explosion. The last nuclear test by the United States was on September 23, 1992; the U.S. has signed but not ratified the Comprehensive Nuclear-Test-Ban Treaty . Currently, the United States nuclear arsenal is deployed in three areas: The United States is one of the five "Nuclear Weapons States" under
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3008-703: The F/A-18 Hornet , F-15E , F-16 , F-22 and F-35 . Some 350 of these bombs are deployed at seven airbases in six European NATO countries; of these, 180 tactical B61 nuclear bombs fall under a nuclear sharing arrangement. The U.S. Navy currently has 18 Ohio -class submarines deployed, of which 14 are ballistic missile submarines . Each submarine is equipped with a maximum complement of 24 Trident II missiles. Approximately 12 U.S. attack submarines were equipped to launch nuclear Tomahawk missiles , but these weapons were removed from service by 2013. The number of Deployed and Non-Deployed SLBMs on
3102-1015: The Geneva Protocol on January 22, 1975. The U.S. ratified the Biological Weapons Convention (BWC) which came into effect in March 1975. Negotiations for a legally binding verification protocol to the BWC proceeded for years. In 2001, negotiations ended when the Bush administration rejected an effort by other signatories to create a protocol for verification, arguing that it could be abused to interfere with legitimate biological research. The U.S. Army Medical Research Institute of Infectious Diseases , located in Fort Detrick, produces small quantities of biological agents, for use in biological weapons defense research. According to
3196-695: The Starfish Prime high-altitude nuclear test in 1962, an unexpected effect was produced which is called a nuclear electromagnetic pulse . This is an intense flash of electromagnetic energy produced by a rain of high-energy electrons which in turn are produced by a nuclear bomb's gamma rays. This flash of energy can permanently destroy or disrupt electronic equipment if insufficiently shielded. It has been proposed to use this effect to disable an enemy's military and civilian infrastructure as an adjunct to other nuclear or conventional military operations. By itself it could as well be useful to terrorists for crippling
3290-541: The Treaty on the Non-Proliferation of Nuclear Weapons (1968) attempted to place restrictions on the types of activities signatories could participate in, with the goal of allowing the transference of non-military nuclear technology to member countries without fear of proliferation. United States and weapons of mass destruction The United States is known to have possessed three types of weapons of mass destruction : nuclear , chemical , and biological weapons . As
3384-586: The Treaty on the Non-Proliferation of Nuclear Weapons , which the U.S. ratified in 1968. On October 13, 1999, the U.S. Senate rejected ratification of the Comprehensive Test Ban Treaty , having previously ratified the Partial Test Ban Treaty in 1963. The U.S. has not, however, tested a nuclear weapon since 1992, though it has tested many non-nuclear components and has developed powerful supercomputers to duplicate
3478-554: The Tsar Bomba (see TNT equivalent ). A thermonuclear weapon weighing as little as 600 pounds (270 kg) can release energy equal to more than 1.2 megatonnes of TNT (5.0 PJ). A nuclear device no larger than a conventional bomb can devastate an entire city by blast, fire, and radiation . Since they are weapons of mass destruction , the proliferation of nuclear weapons is a focus of international relations policy. Nuclear weapons have been deployed twice in war , both by
3572-676: The Tsar Bomba of the USSR, which released an energy equivalent of over 50 megatons of TNT (210 PJ), was a three-stage weapon. Most thermonuclear weapons are considerably smaller than this, due to practical constraints from missile warhead space and weight requirements. In the early 1950s the Livermore Laboratory in the United States had plans for the testing of two massive bombs, Gnomon and Sundial , 1 gigaton of TNT and 10 gigatons of TNT respectively. Fusion reactions do not create fission products, and thus contribute far less to
3666-490: The United States Congress in 2004 eliminated funding for some of this research including the " bunker-busting or earth-penetrating" weapons. The exact number of nuclear weapons possessed by the United States is difficult to determine. Different treaties and organizations have different criteria for reporting nuclear weapons, especially those held in reserve, and those being dismantled or rebuilt: In 2002,
3760-424: The hafnium controversy ) have been proposed as possible triggers for conventional thermonuclear reactions. Antimatter , which consists of particles resembling ordinary matter particles in most of their properties but having opposite electric charge , has been considered as a trigger mechanism for nuclear weapons. A major obstacle is the difficulty of producing antimatter in large enough quantities, and there
3854-614: The head of government or head of state . Despite controls and regulations governing nuclear weapons, there is an inherent danger of "accidents, mistakes, false alarms, blackmail, theft, and sabotage". In the late 1940s, lack of mutual trust prevented the United States and the Soviet Union from making progress on arms control agreements. The Russell–Einstein Manifesto was issued in London on July 9, 1955, by Bertrand Russell in
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3948-496: The nuclear fission and hydrogen bombs (the latter involving nuclear fusion ). It was the world's first and only nuclear power for four years, from 1945 until 1949, when the Soviet Union produced its own nuclear weapon . The United States has the second-largest number of nuclear weapons in the world, after the Russian Federation . Nuclear weapons have been used twice in combat: two nuclear weapons were used by
4042-436: The tropopause into the stratosphere , where the calm non-turbulent winds permit the debris to travel great distances from the burst, eventually settling and unpredictably contaminating areas far removed from the target of the explosion. There are other types of nuclear weapons as well. For example, a boosted fission weapon is a fission bomb that increases its explosive yield through a small number of fusion reactions, but it
4136-537: The "implosion" method, is more sophisticated and more efficient (smaller, less massive, and requiring less of the expensive fissile fuel) than the former. A major challenge in all nuclear weapon designs is to ensure that a significant fraction of the fuel is consumed before the weapon destroys itself. The amount of energy released by fission bombs can range from the equivalent of just under a ton to upwards of 500,000 tons (500 kilotons ) of TNT (4.2 to 2.1 × 10 GJ). All fission reactions generate fission products ,
4230-586: The 1980s (though not deployed in Europe) for use as tactical payloads for US Army artillery shells (200 mm W79 and 155 mm W82 ) and short range missile forces. Soviet authorities announced similar intentions for neutron warhead deployment in Europe; indeed, they claimed to have originally invented the neutron bomb, but their deployment on USSR tactical nuclear forces is unverifiable. A type of nuclear explosive most suitable for use by ground special forces
4324-425: The Cold War, policy and military theorists considered the sorts of policies that might prevent a nuclear attack, and they developed game theory models that could lead to stable deterrence conditions. Different forms of nuclear weapons delivery (see above) allow for different types of nuclear strategies. The goals of any strategy are generally to make it difficult for an enemy to launch a pre-emptive strike against
4418-494: The Joint Chiefs of Staffs website Publication, "Integration of nuclear weapons employment with conventional and special operations forces is essential to the success of any mission or operation." Because they are weapons of mass destruction, the proliferation and possible use of nuclear weapons are important issues in international relations and diplomacy. In most countries, the use of nuclear force can only be authorized by
4512-503: The Nuclear Age (1961) that mere possession of a nuclear arsenal was enough to ensure deterrence, and thus concluded that the spread of nuclear weapons could increase international stability . Some prominent neo-realist scholars, such as Kenneth Waltz and John Mearsheimer , have argued, along the lines of Gallois, that some forms of nuclear proliferation would decrease the likelihood of total war , especially in troubled regions of
4606-662: The Ohio-Class SSBNs as of 2018 is 280, of which 203 SLBMs are deployed. The United States offensive biological weapons program was instigated by President Franklin Roosevelt and the U.S. Secretary of War in October 1941. Research occurred at several sites. A production facility was built at Terre Haute, Indiana , but testing with a benign agent demonstrated contamination of the facility so no production occurred during World War II . The US government and military
4700-521: The U.S. government, this research is performed in full accordance with the BWC. In September 2001, shortly after the September 11 attacks on the United States, there was a series of anthrax attacks aimed at U.S. media offices and the U.S. Senate which killed five people. The anthrax used in the attacks was the Ames strain , which was first studied at Fort Detrick and then distributed to other labs around
4794-554: The U.S. in the Korean (1950–53) conflict has never been substantiated. In late 1969, President Richard Nixon unilaterally renounced the first use of chemical weapons (as well as all methods of biological warfare). He issued a unilateral decree halting production and transport of chemical weapons which remains in effect. From 1967 to 1970 in Operation CHASE , the U.S. disposed of chemical weapons by sinking ships laden with
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#17327807179074888-464: The U.S. to destroying all chemical weapons and renounced the right to chemical weapon retaliation. In 1993, the U.S. signed the CWC, which required the destruction of all chemical weapon agents, dispersal systems, chemical weapons production facilities by 2012. Both Russia and U.S. missed the CWC's extended deadline of April 2012 to destroy all of their chemical weapons. The United States destroyed 89.75% of
4982-663: The U.S. was party. Stockpile reductions began in the 1980s, with the removal of some outdated munitions and destruction of the entire stock of BZ beginning in 1988. In 1990, destruction of chemical agents stored on Johnston Atoll in the Pacific began, seven years before the Chemical Weapons Convention (CWC) came into effect. In 1986, President Ronald Reagan began removal of the U.S. stockpile of chemical weapons from Germany (see Operation Steel Box ). In 1991, President George H. W. Bush unilaterally committed
5076-623: The UK and the Warsaw Pact, separately, introduced proposals to the UN to ban biological weapons, which would lead to a treaty in 1972. The U.S. cancelled its offensive biological weapons program by executive order in November 1969 (microorganisms) and February 1970 (toxins) and ordered the destruction of all offensive biological weapons, which occurred between May 1971 and February 1973. The U.S. ratified
5170-626: The US military also released fungal spores at the Norfolk Naval Supply Center on African-American workers to see if they are more susceptible to the pathogen than Caucasians. In 1966, the US government released Bacillus globigii on the New York Subway to research how a civilian population can be used to spread pathogens. It is claimed many of those exposed were later found to exhibit long-term medical conditions of which
5264-664: The USAAF detonated a plutonium implosion-type fission bomb nicknamed " Fat Man " over the Japanese city of Nagasaki . These bombings caused injuries that resulted in the deaths of approximately 200,000 civilians and military personnel . The ethics of these bombings and their role in Japan's surrender are to this day, still subjects of debate . Since the atomic bombings of Hiroshima and Nagasaki , nuclear weapons have been detonated over 2,000 times for testing and demonstration. Only
5358-777: The USAF AIR-2 Genie , the AIM-26 Falcon and US Army Nike Hercules . Missile interceptors such as the Sprint and the Spartan also used small nuclear warheads (optimized to produce neutron or X-ray flux) but were for use against enemy strategic warheads. Other small, or tactical, nuclear weapons were deployed by naval forces for use primarily as antisubmarine weapons. These included nuclear depth bombs or nuclear armed torpedoes. Nuclear mines for use on land or at sea are also possibilities. The system used to deliver
5452-527: The United States against the Japanese cities of Hiroshima and Nagasaki in 1945 during World War II . Nuclear weapons have only twice been used in warfare, both times by the United States against Japan at the end of World War II . On August 6, 1945, the United States Army Air Forces (USAAF) detonated a uranium gun-type fission bomb nicknamed " Little Boy " over the Japanese city of Hiroshima ; three days later, on August 9,
5546-438: The United States against Japan during World War II in the atomic bombings of Hiroshima and Nagasaki . Altogether, the two bombings killed 105,000 people and injured thousands more while devastating hundreds or thousands of military bases , factories , and cottage industries . The U.S. conducted an extensive nuclear testing program. 1054 tests were conducted between 1945 and 1992. The exact number of nuclear devices detonated
5640-533: The United States and Russia agreed in the SORT treaty to reduce their deployed stockpiles to not more than 2,200 warheads each. In 2003, the U.S. rejected Russian proposals to further reduce both nation's nuclear stockpiles to 1,500 each. In 2007, for the first time in 15 years, the United States built new warheads. These replaced some older warheads as part of the Minuteman III upgrade program. 2007 also saw
5734-526: 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 of combining sufficient yield with portability limits their military utility. Nuclear warfare strategy is a set of policies that deal with preventing or fighting a nuclear war. The policy of trying to prevent an attack by
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#17327807179075828-554: The W93 and sharing some non-nuclear components. The warhead is expected to incorporate improved safety features such as insensitive high explosives . According to the Energy Department , the design will be based on previously tested nuclear components and will not require nuclear testing. However, some critics have called for testing the new design to ensure safety and reliability. Nuclear warhead A nuclear weapon
5922-485: The chance of a 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 difficult. Tactical weapons 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 has been tested by
6016-409: The country that invented nuclear weapons, the U.S. is the only country to have used nuclear weapons on another country, when it detonated two atomic bombs over two Japanese cities of Hiroshima and Nagasaki during World War II . It had secretly developed the earliest form of the atomic weapon during the 1940s under the title " Manhattan Project ". The United States pioneered the development of both
6110-435: The creation of nuclear fallout than fission reactions, but because all thermonuclear weapons contain at least one fission stage, and many high-yield thermonuclear devices have a final fission stage, thermonuclear weapons can generate at least as much nuclear fallout as fission-only weapons. Furthermore, high yield thermonuclear explosions (most dangerously ground bursts) have the force to lift radioactive debris upwards past
6204-399: The decision process. The prospect of mutually assured destruction might not deter an enemy who expects to die in the confrontation. Further, if the initial act is from a stateless terrorist instead of a sovereign nation, there might not be a nation or specific target to retaliate against. It has been argued, especially after the September 11, 2001, attacks , that this complication calls for
6298-469: The energy of a fission bomb to compress and heat fusion fuel. In the Teller-Ulam design , which accounts for all multi-megaton yield hydrogen bombs, this is accomplished by placing a fission bomb and fusion fuel ( tritium , deuterium , or lithium deuteride ) in proximity within a special, radiation-reflecting container. When the fission bomb is detonated, gamma rays and X-rays emitted first compress
6392-742: The first Minuteman III missiles removed from service as part of the drawdown. Overall, stockpiles and deployment systems continue to decline in number under the terms of the New START treaty. In 2014, Bulletin of the Atomic Scientists released a report, stating that there are a total of 2,530 warheads kept in reserve, and 2,120 actively deployed. Of the warheads actively deployed, the number of strategic warheads rests at 1,920 (subtracting 200 tactical B61s as part of Nato nuclear weapon sharing arrangements). The amount of warheads being actively disabled rests at about 2,700 warheads, which brings
6486-455: The fission bomb core. The external method of boosting enabled the USSR to field the first partially thermonuclear weapons, but it is now obsolete because it demands a spherical bomb geometry, which was adequate during the 1950s arms race when bomber aircraft were the only available delivery vehicles. The detonation of any nuclear weapon is accompanied by a blast of neutron radiation . Surrounding
6580-420: The fusion fuel, then heat it to thermonuclear temperatures. The ensuing fusion reaction creates enormous numbers of high-speed neutrons , which can then induce fission in materials not normally prone to it, such as depleted uranium . Each of these components is known as a "stage", with the fission bomb as the "primary" and the fusion capsule as the "secondary". In large, megaton-range hydrogen bombs, about half of
6674-535: The globe, would make all life on the planet extinct. In connection with the Strategic Defense Initiative , research into the nuclear pumped laser was conducted under the DOD program Project Excalibur but this did not result in a working weapon. The concept involves the tapping of the energy of an exploding nuclear bomb to power a single-shot laser that is directed at a distant target. During
6768-461: The knowledge gained from testing without conducting the actual tests themselves. In the early 1990s, the U.S. stopped developing new nuclear weapons and now devotes most of its nuclear efforts into stockpile stewardship , maintaining and dismantling its now-aging arsenal. The administration of George W. Bush decided in 2003 to engage in research towards a new generation of small nuclear weapons, especially "earth penetrators". The budget passed by
6862-496: The majority of their energy from nuclear fission reactions alone, and those that use fission reactions to begin nuclear fusion reactions that produce a large amount of the total energy output. All existing nuclear weapons derive some of their explosive energy from nuclear fission reactions. Weapons whose explosive output is exclusively from fission reactions are commonly referred to as atomic bombs or atom bombs (abbreviated as A-bombs ). This has long been noted as something of
6956-407: The midst of the Cold War. It highlighted the dangers posed by nuclear weapons and called for world leaders to seek peaceful resolutions to international conflict. The signatories included eleven pre-eminent intellectuals and scientists, including Albert Einstein , who signed it just days before his death on April 18, 1955. A few days after the release, philanthropist Cyrus S. Eaton offered to sponsor
7050-545: The military establishment have questioned the usefulness of such weapons in the current military climate. According to an advisory opinion issued by the International Court of Justice in 1996, the use of (or threat of use of) such weapons would generally be contrary to the rules of international law applicable in armed conflict, but the court did not reach an opinion as to whether or not the threat or use would be lawful in specific extreme circumstances such as if
7144-589: The military has denied causation. The US government continued similar experiments on civilian populations in other cities across the country until the early 1970s. The Dugway Proving Ground facility in Utah , opened in 1942, to this day tests and stores biological weapons. In 1968, the facility infamously poisoned 6,000 sheep with the nerve agent VX. The 800,000 acre facility has reportedly weaponized fleas, mosquitoes, as well as conducted experiments on both animal and human subjects. A more advanced production facility
7238-408: The missiles before they land or implementing civil defense measures using early-warning systems to evacuate citizens to safe areas before an attack. Weapons designed to threaten large populations or to deter attacks are known as strategic weapons . Nuclear weapons for use on a battlefield in military situations are called tactical weapons . Critics of nuclear war strategy often suggest that
7332-613: The most nuclear warheads sitting at 5,977, while the United States has 5,428 warheads. The U.S. Air Force currently operates 400 Minuteman III ICBMs , located primarily in the northern Rocky Mountain states and the Dakotas . Peacekeeper missiles were phased out of the Air Force inventory in 2005. All USAF Minuteman II missiles were destroyed in accordance with the START treaty and their launch silos imploded and buried then sold to
7426-549: The original stockpile of nearly 31,100 metric tons (30,609 long tons ) of nerve and mustard agents under the terms of the treaty. Chemical weapons destruction resumed in 2015. The country's last stockpile was at the Blue Grass Army Depot in Kentucky. The U.S. destroyed its final chemical weapon on July 7, 2023. The final weapon to be destroyed was a sarin nerve agent -filled M55 rocket . The total cost for
7520-549: The public under the START II . The U.S. goal under the SORT treaty was to reduce from 1,600 warheads deployed on over 500 missiles in 2003 to 500 warheads on 450 missiles in 2012. The first Minuteman III were removed under this plan in 2007 while, at the same time, the warheads deployed on Minuteman IIIs began to be upgraded from smaller W62s to larger W87s from decommissioned Peacekeeper missiles. The U.S. Air Force also operates
7614-428: The remains of the split atomic nuclei. Many fission products are either highly radioactive (but short-lived) or moderately radioactive (but long-lived), and as such, they are a serious form of radioactive contamination . Fission products are the principal radioactive component of nuclear fallout . Another source of radioactivity is the burst of free neutrons produced by the weapon. When they collide with other nuclei in
7708-402: The surrounding material, the neutrons transmute those nuclei into other isotopes, altering their stability and making them radioactive. The most commonly used fissile materials for nuclear weapons applications have been uranium-235 and plutonium-239 . Less commonly used has been uranium-233 . Neptunium-237 and some isotopes of americium may be usable for nuclear explosives as well, but it
7802-498: The survival of the state were at stake. Another deterrence position is that nuclear proliferation can be desirable. In this case, it is argued that, unlike conventional weapons, nuclear weapons deter all-out war between states, and they succeeded in doing this during the Cold War between the U.S. and the Soviet Union . In the late 1950s and early 1960s, Gen. Pierre Marie Gallois of France, an adviser to Charles de Gaulle , argued in books like The Balance of Terror: Strategy for
7896-459: The total United States inventory to about 7,400 warheads. The U.S. government decided not to sign the UN treaty on the Prohibition of Nuclear Weapons , a binding agreement for negotiations for the total elimination of nuclear weapons, supported by more than 120 nations. As of early 2019, more than 90% of world's 13,865 nuclear weapons were owned by the United States and Russia. Russia has
7990-482: The war, all of the former Allies pursued further research on the three new nerve agents developed by the Nazis: tabun , sarin , and soman . Over the following decades, thousands of American military volunteers were exposed to chemical agents during Cold War testing programs, as well as in accidents. (In 1968, one such accident killed approximately 6,400 sheep when an agent drifted out of Dugway Proving Ground during
8084-446: The weapon system and difficult to defend against the delivery of the weapon during a potential conflict. This can mean keeping weapon locations hidden, such as deploying them on submarines or land mobile transporter erector launchers whose locations are difficult to track, or it can mean protecting weapons by burying them in hardened missile silo bunkers. Other components of nuclear strategies included using missile defenses to destroy
8178-443: The weapons in the deep Atlantic . The U.S. began to research safer disposal methods for chemical weapons in the 1970s, destroying several thousand tons of mustard gas by incineration and nearly 4,200 tons of nerve agent by chemical neutralization. The U.S. entered the Geneva Protocol in 1975 (the same time it ratified the Biological Weapons Convention ). This was the first operative international treaty on chemical weapons to which
8272-631: The world where there exists a single nuclear-weapon state. Aside from the public opinion that opposes proliferation in any form, there are two schools of thought on the matter: those, like Mearsheimer, who favored selective proliferation, and Waltz, who was somewhat more non- interventionist . Interest in proliferation and the stability-instability paradox that it generates continues to this day, with ongoing debate about indigenous Japanese and South Korean nuclear deterrent against North Korea . The threat of potentially suicidal terrorists possessing nuclear weapons (a form of nuclear terrorism ) complicates
8366-490: The world. In World War I , the U.S. had its own chemical weapons program, which produced its own chemical munitions, including phosgene and mustard gas . The U.S. only created about 4% of the total chemical weapons produced for that war and just over 1% of the era's most effective weapon, mustard gas. (U.S. troops suffered less than 6% of gas casualties.) Although the U.S. had begun a large-scale production of Lewisite , for use in an offensive planned for early 1919, Lewisite
8460-624: The yield comes from the final fissioning of depleted uranium. Virtually all thermonuclear weapons deployed today use the "two-stage" design described to the right, but it is possible to add additional fusion stages—each stage igniting a larger amount of fusion fuel in the next stage. This technique can be used to construct thermonuclear weapons of arbitrarily large yield. This is in contrast to fission bombs, which are limited in their explosive power due to criticality danger (premature nuclear chain reaction caused by too-large amounts of pre-assembled fissile fuel). The largest nuclear weapon ever detonated,
8554-518: Was carrying mustard gas. The presence of the gas was highly classified, and, 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 affair was kept secret at the time and for many years. After the war, the U.S. both participated in arms control talks involving chemical weapons and continued to stockpile them, eventually exceeding 30,000 tons of material. After
8648-510: Was constructed in Pine Bluff, Arkansas , which began producing biological agents in 1954. Fort Detrick , Maryland , later became a production facility as well as a research site. The U.S. developed anti-personnel and anti-crop biological weapons. Several deployment systems were developed including aerial spray tanks, aerosol spray canisters, grenades, rocket warheads and cluster bombs. (See also U.S. Biological Weapon Testing ) In mid-1969,
8742-596: Was not deployed during World War I. The United States also created a special unit, the 1st Gas Regiment, which used phosgene in attacks after being deployed to France. Chemical weapons were not used by the Allies or Germany during World War II for military purposes, but such weapons were deployed to Europe from the United States. In 1943, German bombers attacked the port of Bari in Southern Italy, sinking several American ships – among them John Harvey , which
8836-744: Was the Special Atomic Demolition Munition , or SADM, sometimes popularly known as a suitcase nuke . This is a nuclear bomb that is man-portable, or at least truck-portable, and though of a relatively small yield (one or two kilotons) is sufficient to destroy important tactical targets such as bridges, dams, tunnels, important military or commercial installations, etc. either behind enemy lines or pre-emptively on friendly territory soon to be overtaken by invading enemy forces. These weapons require plutonium fuel and are particularly "dirty". They also demand especially stringent security precautions in their storage and deployment. Small "tactical" nuclear weapons were deployed for use as antiaircraft weapons. Examples include
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