141-746: The W84 is an American thermonuclear warhead initially designed for use on the BGM-109G Gryphon Ground Launched Cruise Missile (GLCM) . The weapon was designed by Lawrence Livermore National Laboratory beginning in September 1978 for the Ground Launched Cruise Missile program. Production engineering began in December 1980 and first production began in June 1983 with full-scale production starting in September 1983. Though
282-410: A hohlraum or radiation case. The "George" shot of Operation Greenhouse of 9 May 1951 tested the basic concept for the first time on a very small scale. As the first successful (uncontrolled) release of nuclear fusion energy, which made up a small fraction of the 225 kt (940 TJ ) total yield, it raised expectations to a near certainty that the concept would work. On 1 November 1952,
423-417: A nuclear fission primary stage (fueled by U or Pu ) and a separate nuclear fusion secondary stage containing thermonuclear fuel: heavy isotopes of hydrogen ( deuterium and tritium ) as the pure element or in modern weapons lithium deuteride . For this reason, thermonuclear weapons are often colloquially called hydrogen bombs or H-bombs . A fusion explosion begins with
564-730: A secondary section that consists of fusion fuel . The energy released by the primary compresses the secondary through the process of radiation implosion , at which point it is heated and undergoes nuclear fusion . This process could be continued, with energy from the secondary igniting a third fusion stage; the Soviet Union's AN602 " Tsar Bomba " is thought to have been a three-stage fission-fusion-fusion device. Theoretically by continuing this process thermonuclear weapons with arbitrarily high yield could be constructed. This contrasts with fission weapons, which are limited in yield because only so much fission fuel can be amassed in one place before
705-585: A date for the commencement of service of a replacement to the current system. France tested its first nuclear weapon in 1960 (" Gerboise Bleue "), based mostly on its own research. It was motivated by the Suez Crisis diplomatic tension in relation to both the Soviet Union and its allies, the United States and United Kingdom. It was also relevant to retain great power status, alongside the United Kingdom, during
846-422: A decision. Some countries are known to have delegated launch authority to military personnel in the event that the usual launch authority is incapacitated; whether or not the 'pre-delegated' authority exists at any particular time is kept secret. In the United States, some military commanders have been delegated authority to launch nuclear weapons "when the urgency of time and circumstances clearly does not permit
987-430: A design could not produce thermonuclear weapons whose explosive yields could be made arbitrarily large (unlike U.S. designs at that time). The fusion layer wrapped around the fission core could only moderately multiply the fission energy (modern Teller–Ulam designs can multiply it 30-fold). Additionally, the whole fusion stage had to be imploded by conventional explosives, along with the fission core, substantially increasing
1128-487: A dozen megatons, which was generally considered enough to destroy even the most hardened practical targets (for example, a control facility such as the Cheyenne Mountain Complex ). Even such large bombs have been replaced by smaller yield nuclear bunker buster bombs. For destruction of cities and non-hardened targets, breaking the mass of a single missile payload down into smaller MIRV bombs in order to spread
1269-456: A few specific incidents outlined in a section below. The basic principle of the Teller–Ulam configuration is the idea that different parts of a thermonuclear weapon can be chained together in stages, with the detonation of each stage providing the energy to ignite the next stage. At a minimum, this implies a primary section that consists of an implosion-type fission bomb (a "trigger"), and
1410-619: A fleet of V bomber strategic bombers and ballistic missile submarines (SSBNs) equipped with nuclear weapons during the Cold War. The Royal Navy currently maintains a fleet of four Vanguard -class ballistic missile submarines equipped with Trident II missiles . In 2016, the UK House of Commons voted to renew the British nuclear weapons system with the Dreadnought -class submarine , without setting
1551-602: A full-scale invasion , with limited responses by the other signatories. Up until the 1990s the US had stationed nuclear weapons outside of its territories and sharing countries. During the Cold War , specifically during the presidency of Ferdinand Marcos from 1965 to 1986, American nuclear warheads were secretly stockpiled in the Philippines . Taiwan was developing capacities to construct nuclear weapons up until 1988. Before 1974,
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#17328581274831692-453: A high-yield explosion. A W88 warhead manages to yield up to 475 kilotonnes of TNT (1,990 TJ) with a physics package 68.9 inches (1,750 mm) long, with a maximum diameter of 21.8 inches (550 mm), and by different estimates weighing in a range from 175 to 360 kilograms (386 to 794 lb). The smaller warhead allows more of them to fit onto a single missile and improves basic flight properties such as speed and range. The idea of
1833-473: A low-powered thermonuclear detonation; NORSAR estimates the yield at 250 kilotons of TNT. In 2018, North Korea announced a halt in nuclear weapons tests and made a conditional commitment to denuclearisation of the Korean Peninsula ; however, in December 2019, it indicated it no longer considered itself bound by the moratorium. Kim Jong Un officially declared North Korea a nuclear weapons state during
1974-483: A massive effort was mounted to re-invent the process. An impurity crucial to the properties of the old Fogbank was omitted during the new process. Only close analysis of new and old batches revealed the nature of that impurity. The manufacturing process used acetonitrile as a solvent , which led to at least three evacuations of the Fogbank plant in 2006. Widely used in the petroleum and pharmaceutical industries, acetonitrile
2115-693: A new modification of the W80 , the W80 Mod 4 was chosen instead as neither system met the dimension and weight requirements for the program. The W84 is a derivative of the B61 nuclear bomb design and is a close relative of the W80 warhead used on the AGM-86 ALCM, AGM-129 ACM, and BGM-109 Tomahawk SLCM cruise missiles. It is a two-stage radiation implosion warhead with a variable yield ranging from 0.2 kiloton up to 150 kilotons. The W84
2256-505: A nuclear explosive device. The US had further said it is not its intention to assist India in the design, construction or operation of sensitive nuclear technologies through the transfer of dual-use items. In establishing an exemption for India, the Nuclear Suppliers Group reserved the right to consult on any future issues which might trouble it. As of June 2024, India was estimated to have a stockpile of 172 warheads. Pakistan
2397-666: A nuclear triad , while others have consolidated away from land and air deterrents to submarine-based forces. Percentage of global nuclear warheads by country These five states are known to have detonated a nuclear explosive before 1 January 1967 and are thus nuclear weapons states under the Treaty on the Non-Proliferation of Nuclear Weapons . They also happen to be the UN Security Council 's (UNSC) permanent members with veto power on UNSC resolutions. The United States developed
2538-514: A nuclear weapons program or arsenal. This policy of "nuclear opacity" has been interpreted as an attempt to get the benefits of deterrence with a minimal political cost. Due to a US ban on funding countries that have weapons of mass destruction , Israel would lose around $ 2 billion a year in military and other aid from the US if it admitted to possessing nuclear weapons. According to the Natural Resources Defense Council and
2679-564: A possibility. It was first used in thermonuclear weapons with the W76 thermonuclear warhead and produced at a plant in the Y-12 Complex at Oak Ridge, Tennessee , for use in the W76. Production of Fogbank lapsed after the W76 production run ended. The W76 Life Extension Program required more Fogbank to be made. This was complicated by the fact that the original Fogbank's properties were not fully documented, so
2820-757: A series of steps that included India's announced plan to separate its civil and military nuclear programs in March 2006, the passage of the India–United States Civil Nuclear Agreement by the US Congress in December 2006, the conclusion of a US–India nuclear cooperation agreement in July 2007, approval by the IAEA of an India-specific safeguards agreement, agreement by the Nuclear Suppliers Group to
2961-535: A single year. Israel is generally understood to have been the sixth country to develop nuclear weapons, but does not acknowledge it. It had "rudimentary, but deliverable," nuclear weapons available as early as 1966. Israel is not a party to the NPT. Israel engages in strategic ambiguity , saying it would not be the first country to "introduce" nuclear weapons to the Middle East without confirming or denying that it has
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#17328581274833102-526: A specific decision by the President." Russia has a semi automated Dead Hand system which may allow military commanders to act based on certain pre-defined criteria. British nuclear-armed submarine commanders are issued with " letters of last resort " written by the Prime Minister containing secret instructions which may or may not give them delegated launch authority. Under NATO nuclear weapons sharing ,
3243-514: A speech on 9 September 2022, the country's foundation day . According to the Stockholm International Peace Research Institute (SIPRI) , North Korea's military nuclear programme remains central to its national security strategy and it may have assembled up to 30 nuclear weapons and could produce more. North Korea conducted more than 90 ballistic missile tests during 2022, the highest number it has ever undertaken in
3384-675: A theoretical yield of 100 megatons, reduced to 50 when detonated. After its dissolution in 1991, the Soviet weapons entered officially into the possession of its successor state , the Russian Federation. The Soviet nuclear arsenal contained some 45,000 warheads at its peak (in 1986), more than any other nation had possessed at any point in history; the Soviet Union built about 55,000 nuclear warheads since 1949. The United Kingdom tested its first nuclear weapon (" Hurricane ") in 1952. The UK had provided considerable impetus and initial research for
3525-529: A thermonuclear fusion bomb ignited by a smaller fission bomb was first proposed by Enrico Fermi to his colleague Edward Teller when they were talking at Columbia University in September 1941, at the start of what would become the Manhattan Project . Teller spent much of the Manhattan Project attempting to figure out how to make the design work, preferring it over work on the atomic bomb, and over
3666-409: A third test with still-higher yield on 12 February 2013 (see 2013 North Korean nuclear test ). North Korea claimed to have conducted its first hydrogen-bomb test on 5 January 2016, though measurements of seismic disturbances indicate that the detonation was not consistent with a hydrogen bomb. On 3 September 2017, North Korea detonated a device , which caused a magnitude 6.1 tremor, consistent with
3807-561: A waiver of export restrictions for India, approval by the US Congress and culminating in the signature of US–India agreement for civil nuclear cooperation in October 2008. The US State Department said it made it "very clear that we will not recognize India as a nuclear-weapon state". The United States is bound by the Hyde Act with India and may cease all cooperation with India if India detonates
3948-415: A withdrawal on 10 January 2003, after the United States accused it of having a secret uranium enrichment program and cut off energy assistance under the 1994 Agreed Framework . In February 2005, North Korea claimed to possess functional nuclear weapons, though their lack of a test at the time led many experts to doubt the claim. In October 2006, North Korea stated that, in response to growing intimidation by
4089-642: Is also not a party to the Nuclear Non-Proliferation Treaty. Pakistan covertly developed nuclear weapons over 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. Pakistani Prime Minister Zulfiqar Ali Bhutto promised in 1971 that if India could build nuclear weapons then Pakistan would too, according to him: "We will develop Nuclear stockpiles, even if we have to eat grass." It
4230-634: Is always restricted to a single person or small group of people. The United States and France require their respective presidents to approve the use of nuclear weapons. In the US, the Presidential Emergency Satchel is always handled by a nearby aide unless the President is near a command center. The decision rests with the Prime Minister in the United Kingdom . Information from China
4371-514: Is believed that Pakistan has possessed nuclear weapons since the mid-1980s. The United States continued to certify that Pakistan did not possess such weapons until 1990, when sanctions were imposed under the Pressler Amendment , requiring a cutoff of US economic and military assistance to Pakistan. In 1998, Pakistan conducted its first six nuclear tests at the Ras Koh Hills in response to
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4512-457: Is flammable and toxic. Y-12 is the sole producer of Fogbank. A simplified summary of the above explanation is: How exactly the energy is "transported" from the primary to the secondary has been the subject of some disagreement in the open press but is thought to be transmitted through the X-rays and gamma rays that are emitted from the fissioning primary . This energy is then used to compress
4653-416: Is not sealed. Thermonuclear bomb A thermonuclear weapon , fusion weapon or hydrogen bomb ( H bomb ) is a second-generation nuclear weapon design . Its greater sophistication affords it vastly greater destructive power than first-generation nuclear bombs , a more compact size, a lower mass, or a combination of these benefits. Characteristics of nuclear fusion reactions make possible
4794-487: Is omitted, by replacing the uranium tamper with one made of lead , for example, the overall explosive force is reduced by approximately half but the amount of fallout is relatively low. The neutron bomb is a hydrogen bomb with an intentionally thin tamper, allowing as many of the fast fusion neutrons as possible to escape. Current technical criticisms of the idea of "foam plasma pressure" focus on unclassified analysis from similar high energy physics fields that indicate that
4935-529: Is one order of magnitude greater than the higher proposed plasma pressures and nearly two orders of magnitude greater than calculated radiation pressure. No mechanism to avoid the absorption of energy into the radiation case wall and the secondary tamper has been suggested, making ablation apparently unavoidable. The other mechanisms appear to be unneeded. United States Department of Defense official declassification reports indicate that foamed plastic materials are or may be used in radiation case liners, and despite
5076-462: Is the Soviet early Sloika design. In essence, the Teller–Ulam configuration relies on at least two instances of implosion occurring: first, the conventional (chemical) explosives in the primary would compress the fissile core, resulting in a fission explosion many times more powerful than that which chemical explosives could achieve alone (first stage). Second, the radiation from the fissioning of
5217-437: Is the dominant process that produces radioactive fission product fallout . Before Ivy Mike, Operation Greenhouse in 1951 was the first American nuclear test series to test principles that led to the development of thermonuclear weapons. Sufficient fission was achieved to boost the associated fusion device, and enough was learned to achieve a full-scale device within a year. The design of all modern thermonuclear weapons in
5358-426: Is the fusion fuel, usually a form of lithium deuteride , which is used because it is easier to weaponize than liquefied tritium/deuterium gas. This dry fuel, when bombarded by neutrons, produces tritium, a heavy isotope of hydrogen that can undergo nuclear fusion, along with the deuterium present in the mixture. (See the article on nuclear fusion for a more detailed technical discussion of fusion reactions.) Inside
5499-446: Is the medium by which the outside pressure (force acting on the surface area of the secondary) is transferred to the mass of fusion fuel. The proposed tamper-pusher ablation mechanism posits that the outer layers of the thermonuclear secondary's tamper-pusher are heated so extremely by the primary's X-ray flux that they expand violently and ablate away (fly off). Because total momentum is conserved, this mass of high velocity ejecta impels
5640-453: Is the only US nuclear warhead which has all eight features. These include: insensitive high-explosives, a fire resistant pit, Enhanced Nuclear Detonation Safety (ENDS/EEI) with detonator stronglinks, Command Disable, and the most advanced Cat G Permissive Action Link (PAL). A 2001 declassified report states that the W84 does not use a Canned Subassembly (CSA) and that the weapon's secondary stage
5781-416: Is the primary example). Such processes have resulted in a body of unclassified knowledge about nuclear bombs that is generally consistent with official unclassified information releases and related physics and is thought to be internally consistent, though there are some points of interpretation that are still considered open. The state of public knowledge about the Teller–Ulam design has been mostly shaped from
W84 - Misplaced Pages Continue
5922-549: Is thought to be a standard implosion method fission bomb, though likely with a core boosted by small amounts of fusion fuel (usually 1:1 deuterium : tritium gas) for extra efficiency; the fusion fuel releases excess neutrons when heated and compressed, inducing additional fission. When fired, the Pu or U core would be compressed to a smaller sphere by special layers of conventional high explosives arranged around it in an explosive lens pattern, initiating
6063-489: Is thought to have used multiple stages (including more than one tertiary fusion stage) in their 50 Mt (210 PJ) (100 Mt (420 PJ) in intended use) Tsar Bomba. The fissionable jacket could be replaced with lead, as was done with the Tsar Bomba. If any hydrogen bombs have been made from configurations other than those based on the Teller–Ulam design, the fact of it is not publicly known. A possible exception to this
6204-818: Is unclear, but "the launch of nuclear weapons is commonly believed to rest with the Central Military Commission of the Chinese Communist Party ." Russia grants such power to the President but may also require approval from the Minister of Defence and the Chief of the General Staff . The Supreme Commander of the Armed Forces has authority in North Korea . India, Pakistan and Israel have committees for such
6345-409: Is widely assumed to be beryllium , which fits that description and would also moderate the neutron flux from the primary. Some material to absorb and re-radiate the X-rays in a particular manner may also be used. Candidates for the "special material" are polystyrene and a substance called " Fogbank ", an unclassified codename. Fogbank's composition is classified, though aerogel has been suggested as
6486-463: The Cold War it continued to modernize and enlarge its nuclear arsenal, but from 1992 on has been involved primarily in a program of stockpile stewardship . The US nuclear arsenal contained 31,175 warheads at its Cold War height (in 1966). During the Cold War, the United States built more nuclear weapons than all other nations at approximately 70,000 warheads. The Soviet Union tested its first nuclear weapon (" RDS-1 ") in 1949. This crash project
6627-585: The Federation of American Scientists , Israel likely possesses around 80–400 nuclear weapons. The Stockholm International Peace Research Institute estimates that Israel has approximately 80 intact nuclear weapons, of which 50 are for delivery by Jericho II medium-range ballistic missiles and 30 are gravity bombs for delivery by aircraft. SIPRI also reports that there was renewed speculation in 2012 that Israel may also have developed nuclear-capable submarine-launched cruise missiles . On 7 November 2023, during
6768-526: The Israel–Hamas war , Heritage Minister Amihai Eliyahu said during a radio interview that a nuclear strike would be "one way" to deal with Gaza , which commentators and diplomats interpreted as a tacit admission that Israel possesses such a capability. His remarks were criticized by the United States and Russia, and Eliyahu was subsequently suspended from the Israeli cabinet. The decision to use nuclear weapons
6909-577: The Lop Nur test site. The weapon was developed as a deterrent against both the United States and the Soviet Union. Two years later, China had a fission bomb capable of being put onto a nuclear missile . It tested its first hydrogen bomb (" Test No. 6 ") in 1967, 32 months after testing its first nuclear weapon (the shortest fission-to-fusion development known in history). China is the only NPT nuclear-weapon state to give an unqualified negative security assurance with its " no first use " policy. China acceded to
7050-555: The Non-Aligned Movement have called on all countries to "refrain from nuclear sharing for military purposes under any kind of security arrangements." The Institute of Strategic Studies Islamabad (ISSI) has criticized the arrangement for allegedly violating Articles I and II of the NPT, arguing that "these Articles do not permit the NWS to delegate the control of their nuclear weapons directly or indirectly to others." NATO has argued that
7191-559: The Trident II SLBM, had a prolate primary (code-named Komodo ) and a spherical secondary (code-named Cursa ) inside a specially shaped radiation case (known as the "peanut" for its shape). The value of an egg-shaped primary lies apparently in the fact that a MIRV warhead is limited by the diameter of the primary: if an egg-shaped primary can be made to work properly, then the MIRV warhead can be made considerably smaller yet still deliver
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#17328581274837332-506: The United States , Russia (the successor of the former Soviet Union ), the United Kingdom , France , and China . Of these, the three NATO members, the United Kingdom, the United States, and France, are sometimes termed the P3. Other states that possess nuclear weapons are India , Pakistan , and North Korea . Since the NPT entered into force in 1970, these three states were not parties to
7473-593: The United States Department of Energy has been not to acknowledge the leaking of design information, as such acknowledgment would potentially validate the information as accurate. In a small number of prior cases, the U.S. government has attempted to censor weapons information in the public press , with limited success. According to the New York Times , physicist Kenneth W. Ford defied government orders to remove classified information from his book Building
7614-599: The W-80 the gas expansion velocity is roughly 410 km/s (41 cm/μs) and the implosion velocity 570 km/s (57 cm/μs). The pressure due to the ablating material is calculated to be 5.3 billion bars (530 trillion pascals ) in the Ivy Mike device and 64 billion bars (6.4 quadrillion pascals) in the W-80 device. Comparing the three mechanisms proposed, it can be seen that: The calculated ablation pressure
7755-544: The W47 warhead deployed on Polaris ballistic missile submarines , megaton-class warheads were as small as 18 inches (0.46 m) in diameter and 720 pounds (330 kg) in weight. Further innovation in miniaturizing warheads was accomplished by the mid-1970s, when versions of the Teller–Ulam design were created that could fit ten or more warheads on the end of a small MIRVed missile. The first Soviet fusion design, developed by Andrei Sakharov and Vitaly Ginzburg in 1949 (before
7896-482: The detonation of the fission primary stage. Its temperature soars past 100 million kelvin , causing it to glow intensely with thermal ("soft") X-rays . These X-rays flood the void (the "radiation channel" often filled with polystyrene foam ) between the primary and secondary assemblies placed within an enclosure called a radiation case, which confines the X-ray energy and resists its outward pressure. The distance separating
8037-552: The neutron flux from the primary to prematurely begin heating the secondary, weakening the compression enough to prevent any fusion. There is very little detailed information in the open literature about the mechanism of the interstage. One of the best sources is a simplified diagram of a British thermonuclear weapon similar to the American W80 warhead. It was released by Greenpeace in a report titled "Dual Use Nuclear Technology" . The major components and their arrangement are in
8178-408: The nuclear chain reaction that powers the conventional "atomic bomb". The secondary is usually shown as a column of fusion fuel and other components wrapped in many layers. Around the column is first a "pusher- tamper ", a heavy layer of uranium-238 ( U ) or lead that helps compress the fusion fuel (and, in the case of uranium, may eventually undergo fission itself). Inside this
8319-460: The secondary . The crucial detail of how the X-rays create the pressure is the main remaining disputed point in the unclassified press. There are three proposed theories: The radiation pressure exerted by the large quantity of X-ray photons inside the closed casing might be enough to compress the secondary. Electromagnetic radiation such as X-rays or light carries momentum and exerts a force on any surface it strikes. The pressure of radiation at
8460-651: The "double flash" incident. South Africa acceded to the Nuclear Non-Proliferation Treaty in 1991. In connection with their accession to the NPT, all three countries received assurances that their sovereignty, independence, and territorial integrity would be respected, as stated in the Budapest Memorandum on Security Assurances . These assurances have been flouted by Russia since the Russo-Ukrainian War began in 2014, during which Russia claimed to annex Crimea , occupied Eastern Ukraine , and in 2022, launched
8601-532: The 1980s, but dismantled them in the early 1990s. In 1979, there was a detection of a putative covert nuclear test in the Indian Ocean , called the Vela incident . It has long been speculated that it was a test by Israel, in collaboration with and with the support of South Africa, though this has never been confirmed. South Africa could not have constructed such a nuclear bomb by itself until November 1979, two months after
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#17328581274838742-513: The British fusion bomb, with Sir William Penney in charge of the project. British knowledge on how to make a thermonuclear fusion bomb was rudimentary, and at the time the United States was not exchanging any nuclear knowledge because of the Atomic Energy Act of 1946 . The United Kingdom had worked closely with the Americans on the Manhattan Project. British access to nuclear weapons information
8883-782: The Chinese had more than 500 operational nuclear warheads as of May 2023, and it was on track to posess 1,000 nuclear weapons by the year 2030. India is not a party to the Nuclear Non-Proliferation Treaty . Indian officials rejected the NPT in the 1960s on the grounds that it created a world of nuclear "haves" and "have-nots", arguing that it unnecessarily restricted "peaceful activity" (including "peaceful nuclear explosives"), and that India would not accede to international control of their nuclear facilities unless all other countries engaged in unilateral disarmament of their own nuclear weapons. The Indian position has also asserted that
9024-622: The H Bomb: A Personal History . Ford claims he used only pre-existing information and even submitted a manuscript to the government, which wanted to remove entire sections of the book for concern that foreign states could use the information. Though large quantities of vague data have been officially released—and larger quantities of vague data have been unofficially leaked by former bomb designers—most public descriptions of nuclear weapon design details rely to some degree on speculation, reverse engineering from known information, or comparison with similar fields of physics ( inertial confinement fusion
9165-672: The NPT is in many ways a neo-colonial regime designed to deny security to post-colonial powers. The country tested what is called a " peaceful nuclear explosive " in 1974 (which became known as " Smiling Buddha "). The test was 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 ). India's secret development caused great concern and anger particularly from nations that had supplied its nuclear reactors for peaceful and power generating needs, such as Canada. After its 1974 test, India maintained that its nuclear capability
9306-663: The NPT) and the former Soviet republics of Belarus , Kazakhstan , and Ukraine , whose weapons were transferred to Russia. According to the Federation of American Scientists there are approximately 3,880 active nuclear warheads and 12,119 total nuclear warheads in the world as of 2024. The Stockholm International Peace Research Institute (SIPRI) estimated in 2023 that the total number of nuclear warheads acquired by nuclear states reached 12,512. Approximately 9,576 are kept with military stockpiles. About 3,844 warheads are deployed with missiles. 2,000 warheads, which are primarily from Russia and
9447-428: The Nuclear Non-Proliferation Treaty in 1992. As of 2016, China fielded SLBMs onboard its JL-2 submarines. As of February 2024, China had an estimated total inventory of approximately 500 warheads. According to Stockholm International Peace Research Institute (SIPRI) , China is in the middle of a significant modernization and expansion of its nuclear arsenal. Its nuclear stockpile is expected to continue growing over
9588-674: The Nuclear Non-Proliferation Treaty in 1992. In January 2006, President Jacques Chirac stated a terrorist act or the use of weapons of mass destruction against France would result in a nuclear counterattack. In February 2015, President François Hollande stressed the need for a nuclear deterrent in "a dangerous world". He also detailed the French deterrent as "fewer than 300" nuclear warheads, three sets of 16 submarine-launched ballistic missiles and 54 medium-range air-to-surface missiles and urged other states to show similar transparency. China tested its first nuclear weapon device (" 596 ") in 1964 at
9729-615: The Soviet Union left several former Soviet republics in physical possession of nuclear weapons, although not operational control which was dependent on Russian-controlled electronic Permissive Action Links and the Russian command and control system. Of these, Kazakhstan and Ukraine continue to have neither their own nuclear weapons nor another state's nuclear weapons stationed in their territory whereas Belarus does again claim to have Russian-owned nuclear weapons stationed on its territory since 2023. South Africa produced six nuclear weapons in
9870-521: The Soviets had a working fission bomb), was dubbed the Sloika , after a Russian layer cake , and was not of the Teller–Ulam configuration. It used alternating layers of fissile material and lithium deuteride fusion fuel spiked with tritium (this was later dubbed Sakharov's "First Idea"). Though nuclear fusion might have been technically achievable, it did not have the scaling property of a "staged" weapon. Thus, such
10011-442: The Soviets searched for an alternative design. The "Second Idea", as Sakharov referred to it in his memoirs, was a previous proposal by Ginzburg in November 1948 to use lithium deuteride in the bomb, which would, in the course of being bombarded by neutrons, produce tritium and free deuterium. In late 1953 physicist Viktor Davidenko achieved the first breakthrough of staging the reactions. The next breakthrough of radiation implosion
10152-661: The Teller–Ulam configuration was tested at full scale in the "Ivy Mike" shot at an island in the Enewetak Atoll , with a yield of 10.4 Mt (44 PJ ) (over 450 times more powerful than the bomb dropped on Nagasaki during World War II ). The device, dubbed the Sausage , used an extra-large fission bomb as a "trigger" and liquid deuterium—kept in its liquid state by 20 short tons (18 t ) of cryogenic equipment—as its fusion fuel, and weighed around 80 short tons (73 t ) altogether. The liquid deuterium fuel of Ivy Mike
10293-631: The Treaty and have conducted overt nuclear tests . North Korea had been a party to the NPT but withdrew in 2003. Israel is also generally understood to have nuclear weapons , but does not acknowledge it, maintaining a policy of deliberate ambiguity . Israel is estimated to possess somewhere between 75 and 400 nuclear warheads. One possible motivation for nuclear ambiguity is deterrence with minimum political friction. States that formerly possessed nuclear weapons are South Africa (developed nuclear weapons but then disassembled its arsenal before joining
10434-435: The U.S. and Soviets, achieving only approximately 300 kt (1,300 TJ). The second test Orange Herald was the modified fission bomb and produced 720 kt (3,000 TJ)—making it the largest fission explosion ever. At the time almost everyone (including the pilots of the plane that dropped it) thought that this was a fusion bomb. This bomb was put into service in 1958. A second prototype fusion bomb, Purple Granite ,
10575-485: The United States has provided nuclear weapons for Belgium, Germany, Italy, the Netherlands, and Turkey to deploy and store. This involves pilots and other staff of the "non-nuclear" NATO states practicing, handling, and delivering the US nuclear bombs, and adapting non-US warplanes to deliver US nuclear bombs. However, since all US nuclear weapons are protected with Permissive Action Links , the host states cannot easily arm
10716-525: The United States is known as the Teller–Ulam configuration for its two chief contributors, Edward Teller and Stanisław Ulam , who developed it in 1951 for the United States, with certain concepts developed with the contribution of physicist John von Neumann . Similar devices were developed by the Soviet Union, United Kingdom, France, China and India. The thermonuclear Tsar Bomba was the most powerful bomb ever detonated. As thermonuclear weapons represent
10857-455: The United States maintained around 100 nuclear weapons in Europe, as reflected in the accompanying table. Since June 2023 , the leaders of Russia and Belarus have claimed that a "number of" nuclear weapons are located on Belarusian territory while remaining in Russian possession. Sources hostile to these countries have confirmed that nuclear warheads have been delivered to Belarus, but claim that
10998-405: The United States, are maintained for high operational alerts. The following is a list of states that have acknowledged the possession of nuclear weapons or are presumed to possess them, the approximate number of warheads under their control, and the year they tested their first weapon and their force configuration. This list is informally known in global politics as the "Nuclear Club". With
11139-428: The United States, it would conduct a nuclear test to confirm its nuclear status. North Korea reported a successful nuclear test on 9 October 2006 (see 2006 North Korean nuclear test ). Most US intelligence officials believed that the test was probably only partially successful with a yield of less than a kiloton. North Korea conducted a second, higher-yield test on 25 May 2009 (see 2009 North Korean nuclear test ) and
11280-460: The United States, such knowledge can by default be classified as " Restricted Data ", even if it is created by persons who are not government employees or associated with weapons programs, in a legal doctrine known as " born secret " (though the constitutional standing of the doctrine has been at times called into question; see United States v. Progressive, Inc. ). Born secret is rarely invoked for cases of private speculation. The official policy of
11421-489: The W80. The warhead contains TATB-based LX-17 polymer bonded explosive in its primary stage, which is an insensitive high-explosive (IHE) designed to reduce the chance of detonation in an accident. Other explosive present in the warhead include ultra-fine powdered TATB (UF-TATB) and LX-16, a PETN-based conventional polymer-bonded high explosive. The W84 has all eight of the modern types of nuclear weapon safety features identified as desirable in nuclear weapon safety studies. It
11562-462: The amount of chemical explosives needed. The first Sloika design test, RDS-6s , was detonated in 1953 with a yield equivalent to 400 kt (1,700 TJ) ( 15%- 20% from fusion). Attempts to use a Sloika design to achieve megaton-range results proved unfeasible. After the United States tested the "Ivy Mike" thermonuclear device in November 1952, proving that a multimegaton bomb could be created,
11703-620: The bombs without authorization codes from the US Department of Defense . Former Italian President Francesco Cossiga acknowledged the presence of US nuclear weapons in Italy. US nuclear weapons were also deployed in Canada as well as Greece from 1963. However, the United States withdrew three of the four nuclear-capable weapons systems from Canada by 1972, the fourth by 1984, and all nuclear-capable weapons systems from Greece by 2001. As of April 2019 ,
11844-472: The casing to a plasma, which then re-radiated radiation into the secondary's pusher, causing its surface to ablate and driving it inwards, compressing the secondary, igniting the sparkplug, and causing the fusion reaction. The general applicability of this principle is unclear. In 1999 a reporter for the San Jose Mercury News reported that the U.S. W88 nuclear warhead, a small MIRVed warhead used on
11985-440: The casing's circumference. The neutron guns are tilted so the neutron emitting end of each gun end is pointed towards the central axis of the bomb. Neutrons from each neutron gun pass through and are focused by the neutron focus lens towards the centre of primary in order to boost the initial fissioning of the plutonium. A " polystyrene Polarizer/Plasma Source" is also shown (see below). The first U.S. government document to mention
12126-480: The closing stages of World War II. The project expenditure through 1 October 1945 was reportedly $ 1.845–$ 2 billion, in nominal terms, roughly 0.8 percent of the US GDP in 1945 and equivalent to about $ 32.5 billion today. The United States was the first nation to develop the hydrogen bomb , testing an experimental prototype in 1952 (" Ivy Mike ") and a deployable weapon in 1954 (" Castle Bravo "). Throughout
12267-487: The coming decade and some projections suggest that it will deploy at least as many intercontinental ballistic missiles (ICBMs) as either Russia or the US in that period. However, China's overall nuclear warhead stockpile is still expected to remain smaller than that of either of those states. The Yearbook published by SIPRI in 2023 revealed that China's nuclear warheads stockpile increased by 17% in 2022, reaching 410 warheads. US Department of Defense officials estimate that
12408-412: The conditions needed for fusion, and the idea of staging or placing a separate thermonuclear component outside a fission primary component, and somehow using the primary to compress the secondary. Teller then realized that the gamma and X-ray radiation produced in the primary could transfer enough energy into the secondary to create a successful implosion and fusion burn, if the whole assembly was wrapped in
12549-523: The danger of its accidentally becoming supercritical becomes too great. Surrounding the other components is a hohlraum or radiation case , a container that traps the first stage or primary's energy inside temporarily. The outside of this radiation case, which is also normally the outside casing of the bomb, is the only direct visual evidence publicly available of any thermonuclear bomb component's configuration. Numerous photographs of various thermonuclear bomb exteriors have been declassified. The primary
12690-416: The decision to go forward with the development of the new weapon. Teller and other U.S. physicists struggled to find a workable design. Stanislaw Ulam , a co-worker of Teller, made the first key conceptual leaps towards a workable fusion design. Ulam's two innovations that rendered the fusion bomb practical were that compression of the thermonuclear fuel before extreme heating was a practical path towards
12831-424: The diagram, though details are almost absent; what scattered details it does include likely have intentional omissions or inaccuracies. They are labeled "End-cap and Neutron Focus Lens" and "Reflector Wrap"; the former channels neutrons to the U / Pu Spark Plug while the latter refers to an X-ray reflector; typically a cylinder made of an X-ray opaque material such as uranium with
12972-429: The early conception of the atomic bomb, aided by Austrian, German and Polish physicists working at British universities who had either fled or decided not to return to Nazi Germany or Nazi-controlled territories. The UK collaborated closely with the United States and Canada during the Manhattan Project, but had to develop its own method for manufacturing and detonating a bomb as US secrecy grew after 1945. The United Kingdom
13113-414: The effects of that absorbed energy led to the third mechanism: ablation . The outer casing of the secondary assembly is called the "tamper-pusher". The purpose of a tamper in an implosion bomb is to delay the expansion of the reacting fuel supply (which is very hot dense plasma) until the fuel is fully consumed and the explosion runs to completion. The same tamper material serves also as a pusher in that it
13254-505: The energy of the explosions into a "pancake" area is far more efficient in terms of area-destruction per unit of bomb energy. This also applies to single bombs deliverable by cruise missile or other system, such as a bomber, resulting in most operational warheads in the U.S. program having yields of less than 500 kt (2,100 TJ). In his 1995 book Dark Sun: The Making of the Hydrogen Bomb , author Richard Rhodes describes in detail
13395-522: The entire secondary stage and drives up the density of the plutonium spark plug. The density of the plutonium fuel rises to such an extent that the spark plug is driven into a supercritical state, and it begins a nuclear fission chain reaction . The fission products of this chain reaction heat the highly compressed (and thus super dense) thermonuclear fuel surrounding the spark plug to around 300 million kelvin, igniting fusion reactions between fusion fuel nuclei. In modern weapons fueled by lithium deuteride,
13536-461: The exact number is disputed, either 350 or 530 warheads were produced. The warhead suffered post-deployment design issues after the weapon produced an unexpectedly low yield in a simulated ageing test. This issue was corrected without redesign of the nuclear explosive sub-assembly. One test of the weapon was 2 August 1984 shot Fusileer Correo at a depth of 1,099 feet (335 m), producing a yield of less than 20 kilotonnes of TNT (84 TJ). With
13677-482: 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. In particular, under the Strategic Offensive Reductions Treaty thousands of Russian and US nuclear warheads are inactive in stockpiles awaiting processing. The fissile material contained in
13818-508: The far more powerful Super. The debate covered matters that were alternatively strategic, pragmatic, and moral. In their Report of the General Advisory Committee, Robert Oppenheimer and colleagues concluded that "[t]he extreme danger to mankind inherent in the proposal [to develop thermonuclear weapons] wholly outweighs any military advantage." Despite the objections raised, on 31 January 1950, President Harry S. Truman made
13959-466: The first nuclear weapons during World War II in cooperation with the United Kingdom and Canada as part of the Manhattan Project , out of the apprehension that Nazi Germany would develop them first. It tested the first nuclear weapon on 16 July 1945 (" Trinity ") at 5:30 am, and remains the only country to have used nuclear weapons in war, having bombed the Japanese cities of Hiroshima and Nagasaki in
14100-547: The first transfers were instead made in August 2023. Russia's stated intention is to provide Belarus with two delivery systems: dual-capable Iskander-M missile systems and necessary training and modifications for Belarusian Su-25 aircraft to carry nuclear weapons. The deployment of Russian weapons to Belarus was framed by Russian President Vladimir Putin as being equivalent to the deployments of American nuclear weapons to NATO Allies in Europe under international law. Members of
14241-436: The fissioning of the final natural uranium tamper, something that could not normally be achieved without the neutron flux provided by the fusion reactions in secondary or tertiary stages. Such designs are suggested to be capable of being scaled up to an arbitrary large yield (with apparently as many fusion stages as desired), potentially to the level of a " doomsday device ." However, usually such weapons were not more than
14382-434: The fissioning plutonium spark plug also emits free neutrons that collide with lithium nuclei and supply the tritium component of the thermonuclear fuel. The secondary's relatively massive tamper (which resists outward expansion as the explosion proceeds) also serves as a thermal barrier to keep the fusion fuel filler from becoming too hot, which would spoil the compression. If made of uranium , enriched uranium or plutonium,
14523-609: The five tests conducted by India a few weeks before. In 2004, the Pakistani metallurgist Abdul Qadeer Khan , a key figure in Pakistan's nuclear weapons program, confessed to heading an international black market ring involved in selling nuclear weapons technology. In particular, Khan had been selling gas centrifuge technology to North Korea, Iran, and Libya. Khan denied complicity by the Pakistani government or Army, but this has been called into question by journalists and IAEA officials, and
14664-496: The gap between the Neutron Focus Lens (in the center) and the outer casing near the primary. It separates the primary from the secondary and performs the same function as the previous reflector. There are about six neutron guns (seen here from Sandia National Laboratories ) each protruding through the outer edge of the reflector with one end in each section; all are clamped to the carriage and arranged more or less evenly around
14805-458: The intensities seen in everyday life, such as sunlight striking a surface, is usually imperceptible, but at the extreme intensities found in a thermonuclear bomb the pressure is enormous. For two thermonuclear bombs for which the general size and primary characteristics are well understood, the Ivy Mike test bomb and the modern W-80 cruise missile warhead variant of the W-61 design, the radiation pressure
14946-420: The internal components of the "Ivy Mike" Sausage device, based on information obtained from extensive interviews with the scientists and engineers who assembled it. According to Rhodes, the actual mechanism for the compression of the secondary was a combination of the radiation pressure, foam plasma pressure, and tamper-pusher ablation theories; the radiation from the primary heated the polyethylene foam lining of
15087-492: The interstage was only recently released to the public promoting the 2004 initiation of the Reliable Replacement Warhead (RRW) Program. A graphic includes blurbs describing the potential advantage of a RRW on a part-by-part level, with the interstage blurb saying a new design would replace "toxic, brittle material" and "expensive 'special' material... [that require] unique facilities". The "toxic, brittle material"
15228-524: The last year of the project he was assigned exclusively to the task. However once World War II ended, there was little impetus to devote many resources to the Super , as it was then known. The first atomic bomb test by the Soviet Union in August 1949 came earlier than expected by Americans, and over the next several months there was an intense debate within the U.S. government, military, and scientific communities regarding whether to proceed with development of
15369-415: The layer of fuel is the " spark plug ", a hollow column of fissile material ( Pu or U ) often boosted by deuterium gas. The spark plug, when compressed, can undergo nuclear fission (because of the shape, it is not a critical mass without compression). The tertiary, if one is present, would be set below the secondary and probably be made of the same materials. Separating
15510-432: The low direct plasma pressure they may be of use in delaying the ablation until energy has distributed evenly and a sufficient fraction has reached the secondary's tamper/pusher. Richard Rhodes ' book Dark Sun stated that a 1-inch-thick (25 mm) layer of plastic foam was fixed to the lead liner of the inside of the Ivy Mike steel casing using copper nails. Rhodes quotes several designers of that bomb explaining that
15651-502: The most efficient design for weapon energy yield in weapons with yields above 50 kilotons of TNT (210 TJ), virtually all the nuclear weapons of this size deployed by the five nuclear-weapon states under the Non-Proliferation Treaty today are thermonuclear weapons using the Teller–Ulam design. Detailed knowledge of fission and fusion weapons is classified to some degree in virtually every industrialized country . In
15792-424: The outer radiation case, with the components coming to a thermal equilibrium , and the effects of that thermal energy are then analyzed. The energy is mostly deposited within about one X-ray optical thickness of the tamper/pusher outer surface, and the temperature of that layer can then be calculated. The velocity at which the surface then expands outwards is calculated and, from a basic Newtonian momentum balance,
15933-438: The plastic foam layer inside the outer case is to delay ablation and thus recoil of the outer case: if the foam were not there, metal would ablate from the inside of the outer case with a large impulse, causing the casing to recoil outwards rapidly. The purpose of the casing is to contain the explosion for as long as possible, allowing as much X-ray ablation of the metallic surface of the secondary stage as possible, so it compresses
16074-612: 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 that has now evolved to a dual system based on submarine-launched ballistic missiles (SLBMs) and medium-range air-to-surface missiles ( Rafale fighter-bombers). However, new nuclear weapons are in development and reformed nuclear squadrons were trained during Enduring Freedom operations in Afghanistan . France acceded to
16215-413: The pressure produced by such a plasma would only be a small multiplier of the basic photon pressure within the radiation case, and also that the known foam materials intrinsically have a very low absorption efficiency of the gamma ray and X-ray radiation from the primary. Most of the energy produced would be absorbed by either the walls of the radiation case or the tamper around the secondary. Analyzing
16356-442: The primary and secondary at either end. It does not reflect like a mirror; instead, it gets heated to a high temperature by the X-ray flux from the primary, then it emits more evenly spread X-rays that travel to the secondary, causing what is known as radiation implosion . In Ivy Mike , gold was used as a coating over the uranium to enhance the blackbody effect. Next comes the "Reflector/Neutron Gun Carriage". The reflector seals
16497-425: The primary would be used to compress and ignite the secondary fusion stage, resulting in a fusion explosion many times more powerful than the fission explosion alone. This chain of compression could conceivably be continued with an arbitrary number of tertiary fusion stages, each igniting more fusion fuel in the next stage although this is debated. Finally, efficient bombs (but not so-called neutron bombs ) end with
16638-418: The rest of the tamper-pusher to recoil inwards with tremendous force, crushing the fusion fuel and the spark plug. The tamper-pusher is built robustly enough to insulate the fusion fuel from the extreme heat outside; otherwise, the compression would be spoiled. Rough calculations for the basic ablation effect are relatively simple: the energy from the primary is distributed evenly onto all of the surfaces within
16779-450: The secondary efficiently, maximizing the fusion yield. Plastic foam has a low density, so causes a smaller impulse when it ablates than metal does. Possible variations to the weapon design have been proposed: Most bombs do not apparently have tertiary "stages"—that is, third compression stage(s), which are additional fusion stages compressed by a previous fusion stage. The fissioning of the last blanket of uranium, which provides about half
16920-422: The secondary from the primary is the interstage . The fissioning primary produces four types of energy: 1) expanding hot gases from high explosive charges that implode the primary; 2) superheated plasma that was originally the bomb's fissile material and its tamper; 3) the electromagnetic radiation ; and 4) the neutrons from the primary's nuclear detonation. The interstage is responsible for accurately modulating
17061-580: The secondary stages by radiation implosion. Because of these difficulties, in 1955 Prime Minister Anthony Eden agreed to a secret plan, whereby if the Aldermaston scientists failed or were greatly delayed in developing the fusion bomb, it would be replaced by an extremely large fission bomb. In 1957 the Operation Grapple tests were carried out. The first test, Green Granite, was a prototype fusion bomb that failed to produce equivalent yields compared to
17202-658: The signing of the Intermediate-Range Nuclear Forces Treaty in 1987, the GLCMs that carried the W84 were destroyed and the warheads put into the inactive reserve stockpile . These warheads have been used to study the effects of long-term ageing on TATB and polymer-bonded explosives . The W84 was briefly considered alongside the B61 Mod 12 for the Long-Ranged Stand Off Missile (LRSO) program, but
17343-401: The tamper captures fast fusion neutrons and undergoes fission itself, increasing the overall explosive yield . Additionally, in most designs the radiation case is also constructed of a material that undergoes fission driven by fast thermonuclear neutrons. Such bombs are classified as two stage weapons. Fast fission of the tamper and radiation case is the main contribution to the total yield and
17484-404: The transfer of energy from the primary to the secondary. It must direct the hot gases, plasma, electromagnetic radiation and neutrons toward the right place at the right time. Less than optimal interstage designs have resulted in the secondary failing to work entirely on multiple shots, known as a " fissile fizzle ". The Castle Koon shot of Operation Castle is a good example; a small flaw allowed
17625-406: The two assemblies ensures that debris fragments from the fission primary (which move much more slowly than X-ray photons ) cannot disassemble the secondary before the fusion explosion runs to completion. The secondary fusion stage—consisting of outer pusher/ tamper , fusion fuel filler and central plutonium spark plug—is imploded by the X-ray energy impinging on its pusher/ tamper. This compresses
17766-495: The use of non-fissile depleted uranium as the weapon's main fuel, thus allowing more efficient use of scarce fissile material such as uranium-235 ( U ) or plutonium-239 ( Pu ). The first full-scale thermonuclear test ( Ivy Mike ) was carried out by the United States in 1952, and the concept has since been employed by most of the world's nuclear powers in the design of their weapons. Modern fusion weapons essentially consist of two main components:
17907-412: The velocity at which the rest of the tamper implodes inwards. Applying the more detailed form of those calculations to the Ivy Mike device yields vaporized pusher gas expansion velocity of 290 kilometres per second (29 cm/μs) and an implosion velocity of perhaps 400 km/s (40 cm/μs) if + 3 ⁄ 4 of the total tamper/pusher mass is ablated off, the most energy efficient proportion. For
18048-519: The warheads can then be recycled for use in nuclear reactors . From a high of 70,300 active weapons in 1986, as of 2024 there are approximately 3,880 active nuclear warheads and 12,119 total nuclear warheads in the world. Many of the decommissioned weapons were simply stored or partially dismantled, not destroyed. Additionally, since the dawn of the Atomic Age , the delivery methods of most states with nuclear weapons have evolved—with four acquiring
18189-404: The weapon (with the foam) would be as follows: This would complete the fission-fusion-fission sequence. Fusion, unlike fission, is relatively "clean"—it releases energy but no harmful radioactive products or large amounts of nuclear fallout . The fission reactions though, especially the last fission reactions, release a tremendous amount of fission products and fallout. If the last fission stage
18330-424: The weapons' sharing is compliant with the NPT because "the US nuclear weapons based in Europe are in the sole possession and under constant and complete custody and control of the United States." Nuclear weapons have been present in many nations, often as staging grounds under control of other powers. However, in only one instance has a nation given up nuclear weapons after being in full control of them. The fall of
18471-500: The yield in large bombs, does not count as a "stage" in this terminology. The U.S. tested three-stage bombs in several explosions during Operation Redwing but is thought to have fielded only one such tertiary model, i.e., a bomb in which a fission stage, followed by a fusion stage, finally compresses yet another fusion stage. This U.S. design was the heavy but highly efficient (i.e., nuclear weapon yield per unit bomb weight) 25 Mt (100 PJ) B41 nuclear bomb . The Soviet Union
18612-480: Was calculated to be 73 × 10 ^ bar (7.3 TPa ) for the Ivy Mike design and 1,400 × 10 ^ bar (140 TPa ) for the W-80. Foam plasma pressure is the concept that Chuck Hansen introduced during the Progressive case, based on research that located declassified documents listing special foams as liner components within the radiation case of thermonuclear weapons. The sequence of firing
18753-415: Was cut off by the United States at one point due to concerns about Soviet espionage. Full cooperation was not reestablished until an agreement governing the handling of secret information and other issues was signed. However, the British were allowed to observe the U.S. Castle tests and used sampling aircraft in the mushroom clouds , providing them with clear, direct evidence of the compression produced in
18894-484: Was designed at Lawrence Livermore National Laboratory while the B61 nuclear bomb the design is thought to be based on originated at Los Alamos National Laboratory . The warhead is 13 inches (33 cm) in diameter and 34 inches (86 cm) long which is slightly wider and longer than the W80 warhead used on other cruise missiles from this era. It weighs 388 pounds (176 kg), almost 100 pounds (45 kg) pounds heavier than
19035-405: Was developed partially with information obtained via the atomic spies at the United States' Manhattan Project during and after World War II. The Soviet Union was the second nation to have developed and tested a nuclear weapon. It tested its first megaton-range hydrogen bomb (" RDS-37 ") in 1955. The Soviet Union also tested the most powerful explosive ever detonated by humans, (" Tsar Bomba "), with
19176-545: Was discovered and developed by Sakharov and Yakov Zel'dovich in early 1954. Sakharov's "Third Idea", as the Teller–Ulam design was known in the USSR, was tested in the shot " RDS-37 " in November 1955 with a yield of 1.6 Mt (6.7 PJ). The Soviets demonstrated the power of the staging concept in October 1961, when they detonated the massive and unwieldy Tsar Bomba. It was the largest nuclear weapon developed and tested by any country. In 1954 work began at Aldermaston to develop
19317-509: Was impractical for a deployable weapon, and the next advance was to use a solid lithium deuteride fusion fuel instead. In 1954 this was tested in the " Castle Bravo " shot (the device was code-named Shrimp ), which had a yield of 15 Mt (63 PJ ) (2.5 times expected) and is the largest U.S. bomb ever tested. Efforts shifted towards developing miniaturized Teller–Ulam weapons that could fit into intercontinental ballistic missiles and submarine-launched ballistic missiles . By 1960, with
19458-428: Was later contradicted by statements from Khan himself. As of early 2013, Pakistan was estimated to have had a stockpile of around 140 warheads, and in November 2014 it was projected that by 2020 Pakistan would have enough fissile material for 200 warheads. As of 2024, SIPRI estimated that Pakistan had a stockpile of around 170 warheads. North Korea was a party to the Nuclear Non-Proliferation Treaty, but announced
19599-537: Was primarily "peaceful", but between 1988 and 1990 it apparently weaponized two dozen nuclear weapons for delivery by air. In 1998 India tested weaponized nuclear warheads (" Operation Shakti "), including a thermonuclear device . India adopted a " no first use " policy in 1998. In July 2005, US President George W. Bush and Indian Prime Minister Manmohan Singh announced a civil nuclear cooperation initiative that included plans to conclude an Indo-US civilian nuclear agreement . This initiative came to fruition through
19740-446: Was the third country in the world, after the United States and the Soviet Union, to develop and test a nuclear weapon. Its programme was motivated to have an independent deterrent against the Soviet Union, while also maintaining its status as a great power . It tested its first hydrogen bomb in 1957 ( Operation Grapple ), making it the third country to do so after the United States and Soviet Union. The British Armed Forces maintained
19881-428: Was used in the third test, but only produced approximately 150 kt (630 TJ). List of states with nuclear weapons Eight sovereign states have publicly announced successful detonation of nuclear weapons . Five are considered to be nuclear-weapon states ( NWS ) under the terms of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). In order of acquisition of nuclear weapons, these are
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