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Duck Hook

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Duck Hook (code-named "Pruning Knife" by the military) was the White House code-name of an operation President Richard Nixon had threatened to unleash against North Vietnam during the Vietnam War , if North Vietnam did not yield to Washington's terms at the Paris peace negotiations . Duck Hook called for the possible-nuclear bombing of military and economic targets in and around Hanoi , the mining of Haiphong harbor and other ports, saturation bombing of Hanoi and Haiphong, the bombing of dikes to destroy the food supply of much of the population of North Vietnam, air strikes against North Vietnam's northeast line of communications as well as passes and bridges at the Chinese border, and air and ground attacks on other targets throughout Vietnam.

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117-528: US government documents later declassified reveal that nuclear weapons were considered for Operation Duck Hook. An attachment to a memo from US National Security Advisor Henry Kissinger to Nixon asked, "Should we be prepared to use nuclear weapons?" The memo warned that "Since we cannot confidently predict the exact point at which Hanoi could be likely to respond positively, we must be prepared to play out whatever string necessary ." Kissinger's memo also stated that "To achieve its full effect on Hanoi's thinking,

234-519: A gun-type design in which two sub-critical masses would be brought together by firing a "bullet" into a "target". Richard C. Tolman suggested an implosion-type nuclear weapon , but the proposal attracted little interest. The feasibility of a plutonium bomb was questioned in 1942. Wallace Akers , the director of the British " Tube Alloys " project, told James Bryant Conant on 14 November that James Chadwick had "concluded that plutonium might not be

351-513: 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,

468-651: 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

585-510: A "California Parachute" was approved, a cubical open-rear tail box outer surface with eight radial fins inside of it, four angled at 45 degrees and four perpendicular to the line of fall holding the outer square-fin box to the bomb's rear end. In drop tests in early weeks, the Fat Man missed its target by an average of 1,857 feet (566 m), but this was halved by June as the bombardiers became more proficient with it. The early Y-1222 model Fat Man

702-411: A 0.125-inch-thick (3.2 mm) shell of boron-impregnated plastic. The plastic shell had a 5-inch-diameter (130 mm) cylindrical hole running through it, like the hole in a cored apple, in order to allow insertion of the pit as late as possible. The missing tamper cylinder containing the pit could be slipped in through a hole in the surrounding 18.5-inch-diameter (470 mm) aluminum pusher. The pit

819-597: 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

936-678: 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

1053-458: 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

1170-651: A faster assembly of fissile material than was possible with the gun method, but greatly reduce the amount of material required because of the resulting higher density. The idea that, under such pressures, the plutonium metal would be compressed came from Teller, whose knowledge of how dense metals behaved under heavy pressure was influenced by his pre-war theoretical studies of the Earth's core with George Gamow . The prospect of more-efficient nuclear weapons impressed Oppenheimer, Teller, and Hans Bethe , but they decided that an expert on explosives would be required. Kistiakowsky's name

1287-594: 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

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1404-538: 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

1521-695: A former student of Oppenheimer's who worked on the Manhattan Project. He chose them based on their design shapes; the Thin Man was a very long device, and the name came from the Dashiell Hammett detective novel The Thin Man and series of movies . The Fat Man was round and fat and was named after Sydney Greenstreet 's character in Hammett's The Maltese Falcon . The Little Boy uranium gun-type design came later and

1638-421: 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

1755-611: A gun-type bomb using plutonium was agreed at a meeting in Los Alamos on 17 July 1944. All gun-type work in the Manhattan Project was re-directed towards the Little Boy, enriched uranium gun design, and the Los Alamos Laboratory was reorganized with almost all of the research focused on the problems of implosion for the Fat Man bomb. The idea of using shaped charges as three-dimensional explosive lenses came from James L. Tuck and

1872-472: 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

1989-532: 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

2106-425: 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

2223-411: 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

2340-465: 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

2457-409: 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

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2574-433: 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

2691-421: 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

2808-471: A practical fissionable material for weapons because of impurities". Conant consulted Ernest Lawrence and Arthur Compton , who acknowledged that their scientists at Berkeley and Chicago, respectively, knew about the problem, but they could offer no ready solution. Conant informed Manhattan Project director Brigadier General Leslie R. Groves Jr. , who in turn assembled a special committee consisting of Lawrence, Compton, Oppenheimer, and McMillan to examine

2925-598: A radar approach. At the last minute, however, bombardier Captain Kermit K. Beahan found a hole in the clouds. The Fat Man was dropped and exploded at 11:02 local time, following a 43-second free-fall, at an altitude of about 1,650 feet (500 m). There was poor visibility due to cloud cover, and the bomb missed its intended detonation point by almost two miles, so the damage was somewhat less extensive than that in Hiroshima. An estimated 35,000–40,000 people were killed outright by

3042-411: A ring with a triangular cross-section between them to keep them aligned and prevent jets forming. As plutonium was found to corrode readily, the sphere was coated with nickel. The size of the bomb was constrained by the available aircraft, which were investigated for suitability by Norman Foster Ramsey . The only Allied aircraft considered capable of carrying the Fat Man without major modification were

3159-553: A secret Paris meeting in early August 1969, Kissinger presented to the Vietnamese the US ultimatum to unleash what the US secretly called Duck Hook: "If by November 1 no major progress has been made toward a solution, we will be compelled--with great reluctance--to take measures of the greatest consequence." By October 17, Kissinger recommended against carrying out Operation Duck Hook. On 1 November 1969, Nixon himself decided to abandon it. This

3276-467: A secret tour of the United States. Air Forces personnel used the code names over the phone to make it sound as though they were modifying a plane for Roosevelt and Churchill. Neddermeyer discarded Serber and Tolman's initial concept of implosion as assembling a series of pieces in favor of one in which a hollow sphere was imploded by an explosive shell. He was assisted in this work by Hugh Bradner , Charles Critchfield , and John Streib. L. T. E. Thompson

3393-447: 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

3510-453: A solid subcritical sphere of plutonium could be compressed to a critical state, greatly simplifying the task, since earlier efforts had attempted the more-difficult compression of a hollow spherical shell. After Christy's report, the solid-plutonium core weapon was referred to as the " Christy Gadget ". The task of the metallurgists was to determine how to cast plutonium into a sphere. The difficulties became apparent when attempts to measure

3627-466: A storm and asked if the bomb could be made ready by 9 August. Parsons agreed to try to do so. Fat Man F31 was assembled on Tinian by Project Alberta personnel, and the physics package was fully assembled and wired. It was placed inside its ellipsoidal aerodynamic bombshell, which was painted mustard yellow, and wheeled out, where it was signed by nearly 60 people, including Purnell, Brigadier General Thomas F. Farrell , and Parsons. The acronym "JANCFU"

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3744-691: A strike could be mounted. In March 1948, during the Berlin Blockade , all the assembly teams were in Eniwetok for the Operation Sandstone test, and the military teams were not yet qualified to assemble atomic weapons. In June 1948, General Omar Bradley , Major General Alfred Gruenther and Brigadier General Anthony McAuliffe visited Sandia and Los Alamos to be shown the "special requirements" of atomic weapons. Gruenther asked Brigadier General Kenneth Nichols (hosting): "When are you going to show us

3861-547: 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

3978-420: 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

4095-451: 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

4212-403: 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

4329-481: 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

4446-498: 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

4563-409: 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

4680-490: 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

4797-451: 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

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4914-753: The Boeing B-29 Superfortress Bockscar piloted by Major Charles Sweeney . The name Fat Man refers to the early design of the bomb because it had a wide, round shape. Fat Man was an implosion-type nuclear weapon with a solid plutonium core . The first of that type to be detonated was the Gadget in the Trinity nuclear test less than a month earlier on 16 July at the Alamogordo Bombing and Gunnery Range in New Mexico . Two more were detonated during

5031-702: The Grand Slam , which was much longer but not as wide as the Fat Man. The only American bombers that could carry the Fat Man were the B-29 and the Convair B-36 . In November 1945, the Army Air Forces asked Los Alamos for 200 Fat Man bombs, but there were only two sets of plutonium cores and high-explosive assemblies at the time. The Army Air Forces wanted improvements to the design to make it easier to manufacture, assemble, handle, transport, and stockpile. The wartime Project W-47

5148-655: The Operation Crossroads nuclear tests at Bikini Atoll in 1946, and some 120 were produced between 1947 and 1949, when it was superseded by the Mark 4 nuclear bomb . The Fat Man was retired in 1950. Robert Oppenheimer held conferences in Chicago in June 1942, and in Berkeley, California , in July, at which various engineers and physicists discussed nuclear bomb design issues. They chose

5265-688: 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

5382-447: 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. Fat Man " Fat Man " (also known as Mark III ) was the codename for the type of nuclear weapon

5499-548: 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

5616-663: 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

5733-583: The Type 91 torpedoes released in the attack on Pearl Harbor , was destroyed in the blast. After the war, two Y-1561 Fat Man bombs were used in the Operation Crossroads nuclear tests at Bikini Atoll in the Pacific. The first was known as Gilda after Rita Hayworth 's character in the 1946 movie Gilda , and it was dropped by the B-29 Dave's Dream ; it missed its aim point by 710 yards (650 m). The second bomb

5850-424: 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

5967-599: 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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6084-436: 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

6201-537: 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 ,

6318-578: 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

6435-652: The British Avro Lancaster and the American Boeing B-29 Superfortress . At the time, the B-29 represented the epitome of bomber technology with significant advantages in maximum takeoff weight , range, speed, flight ceiling, and survivability. Without the availability of the B-29, dropping the bomb would likely have been impossible. However, this still constrained the bomb to a maximum length of 11 feet (3.4 m), width of 5 feet (1.5 m) and weight of 20,000 pounds (9,100 kg). Removing

6552-425: 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

6669-488: 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

6786-639: The Mod 0 ended in December 1948, by which time there were still only 53 cores available. It was replaced by improved versions known as Mods 1 and 2 which contained a number of minor changes, the most important of which was that they did not charge the X-Unit firing system's capacitors until released from the aircraft. The Mod 0s were withdrawn from service between March and July 1949, and by October they had all been rebuilt as Mods 1 and 2. Some 120 Mark III Fat Man units were added to

6903-497: 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

7020-492: The Spook and Laggin' Dragon from the 509th Composite Group's 393d Bombardment Squadron , and another from the 216th Army Air Forces Base Unit . The cores were transported to North Field, arriving on 2 August, when F31 was partly disassembled in order to check all its components. F33 was expended near Tinian during a final rehearsal on 8 August. F32 presumably would have been used for a third attack or its rehearsal. On 7 August,

7137-651: 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

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7254-753: 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

7371-515: 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,

7488-457: The United States detonated over the Japanese city of Nagasaki on 9 August 1945. It was the second of the only two nuclear weapons ever used in warfare, the first being Little Boy , and its detonation marked the third nuclear explosion in history. The first one was built by scientists and engineers at Los Alamos Laboratory using plutonium manufactured at the Hanford Site and was dropped from

7605-512: 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

7722-496: The action must be brutal ." [emphasis in original] A few days earlier, a document from two of Kissinger's aides, Roger Morris and Anthony Lake , stated that the President must be prepared "to decide beforehand, the fateful question of how far we will go. He cannot, for example, confront the issue of using tactical nuclear weapons in the midst of the exercise. He must be prepared to play out whatever string necessary in this case." In

7839-458: The aircraft to the heavy defenses of Yahata, but the bombardier was unable to drop visually. By the time of the third bomb run, Japanese anti-aircraft fire was getting close; Second Lieutenant Jacob Beser was monitoring Japanese communications, and he reported activity on the Japanese fighter direction radio bands. Sweeney then proceeded to the alternative target of Nagasaki. It was obscured by clouds as well, and Ashworth ordered Sweeney to make

7956-536: The bomb assembly team, and the Armed Forces Special Weapons Project had only three teams in June 1948. The only aircraft capable of carrying the bomb were Silverplate B-29s, and the only group equipped with them was the 509th Bombardment Group at Walker Air Force Base in Roswell, New Mexico . They would first have to fly to Sandia Base to collect the bombs and then to an overseas base from which

8073-547: The bomb rails allowed a maximum width of 5.5 feet (1.7 m). Drop tests began in March 1944 and resulted in modifications to the Silverplate aircraft due to the weight of the bomb. High-speed photographs revealed that the tail fins folded under the pressure, resulting in an erratic descent. Various combinations of stabilizer boxes and fins were tested on the Fat Man shape to eliminate its persistent wobble until an arrangement dubbed

8190-402: The bomb, and recharging took 72 hours. The batteries had to be removed in any case after nine days or they corroded. The plutonium core could not be left in for much longer, because its heat damaged the high explosives. Replacing the core also required the bomb to be completely disassembled and reassembled. This required about 40 to 50 men and took between 56 and 72 hours, depending on the skill of

8307-487: The bomb, because compressed fissile materials react more rapidly and therefore more completely. Nonetheless, it was decided that the plutonium gun would receive the bulk of the research effort, since it was the project with the least uncertainty involved. It was assumed that the uranium gun-type bomb could be easily adapted from it. The gun-type and implosion-type designs were codenamed " Thin Man " and "Fat Man", respectively. These code names were created by Robert Serber ,

8424-470: The bombing at Nagasaki. A total of 60,000–80,000 fatalities resulted, including from long-term health effects, the strongest of which was leukemia with an attributable risk of 46% for bomb victims. Others died later from related blast and burn injuries, and hundreds more from radiation illnesses from exposure to the bomb's initial radiation. Most of the direct deaths and injuries were among munitions or industrial workers. Mitsubishi's industrial production in

8541-485: 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

8658-487: The city was severed by the attack; the dockyard would have produced at 80 percent of its full capacity within three to four months, the steelworks would have required a year to get back to substantial production, the electric works would have resumed some production within two months and been back at capacity within six months, and the arms plant would have required 15 months to return to 60 to 70 percent of former capacity. The Mitsubishi-Urakami Ordnance Works, which manufactured

8775-435: 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

8892-507: The day after the bombing of Hiroshima, Rear Admiral William R. Purnell , Commodore William S. Parsons , Tibbets, General Carl Spaatz and Major General Curtis LeMay met on Guam to discuss what should be done next. Since there was no indication of Japan surrendering, they decided to proceed with their orders and drop another bomb. Parsons said that Project Alberta would have it ready by 11 August, but Tibbets pointed to weather reports indicating poor flying conditions on that day due to

9009-450: 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

9126-421: The density of plutonium gave inconsistent results. At first contamination was believed to be the cause, but it was soon determined that there were multiple allotropes of plutonium . The brittle α phase that exists at room temperature changes to the plastic β phase at higher temperatures. Attention then shifted to the even more malleable δ phase that normally exists in the 300–450 °C (570–840 °F) range. It

9243-463: 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

9360-411: The fissile material present. The detonation released the energy equivalent to the detonation of 21 kilotons of TNT or 88 terajoules. About 30% of the yield came from fission of the uranium tamper. The first plutonium core was transported with its polonium-beryllium modulated neutron initiator in the custody of Project Alberta courier Raemer Schreiber in a magnesium field carrying case designed for

9477-451: 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

9594-404: The flight engineer notified Sweeney that an inoperative fuel transfer pump made it impossible to use 640 US gallons (2,400 L) of fuel carried in a reserve tank. This fuel would still have to be carried all the way to Japan and back, consuming still more fuel. Replacing the pump would take hours; moving the Fat Man to another aircraft might take just as long and was dangerous as well, as the bomb

9711-419: The form of the isotope plutonium-240 . This has a far higher spontaneous fission rate and radioactivity than plutonium-239 . The cyclotron -produced isotopes, on which the original measurements had been made, held much lower traces of plutonium-240. Its inclusion in reactor-bred plutonium appeared unavoidable. This meant that the spontaneous fission rate of the reactor plutonium was so high that pre-detonation

9828-420: 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

9945-520: 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

10062-611: The issue. The committee concluded that any problems could be overcome simply by requiring higher purity. Oppenheimer reviewed his options in early 1943 and gave priority to the gun-type weapon, but he created the E-5 Group at the Los Alamos Laboratory under Seth Neddermeyer to investigate implosion as a hedge against the threat of pre- detonation . Implosion-type bombs were determined to be significantly more efficient in terms of explosive yield per unit mass of fissile material in

10179-496: 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

10296-407: 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

10413-536: 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

10530-408: 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

10647-417: The purpose by Philip Morrison. Magnesium was chosen because it does not act as a tamper. It left Kirtland Army Air Field on a C-54 transport aircraft of the 509th Composite Group 's 320th Troop Carrier Squadron on 26 July and arrived at North Field on Tinian on 28 July. Three Fat Man high-explosive pre-assemblies (designated F31, F32, and F33) were picked up at Kirtland on 28 July by three B-29s: Luke

10764-499: The real thing? Surely this laboratory monstrosity is not the only type of atomic bomb we have in stockpile?" Nichols told him that better weapons would soon become available. After the "astonishingly good" results of Operation Sandstone were available, stockpiling of improved weapons began. The Soviet Union's first nuclear weapon was based closely on Fat Man's design thanks to spies Klaus Fuchs , Theodore Hall , and David Greenglass , who provided them with secret information concerning

10881-428: 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

10998-412: The same." The bomb was 128.375 inches (3.2607 m) long and 60.25 inches (153.0 cm) in diameter. It weighed 10,265 pounds (4,656 kg). The plutonium pit was 3.62 inches (92 mm) in diameter and contained an "Urchin" modulated neutron initiator that was 0.8 inches (20 mm) in diameter. The depleted uranium tamper was an 8.75-inch-diameter (222 mm) sphere, surrounded by

11115-489: The stockpile between 1947 and 1949, when it was superseded by the Mark 4 nuclear bomb . The Mark III Fat Man was retired in 1950. A nuclear strike would have been a formidable undertaking in the post-war 1940s due to the limitations of the Mark III Fat Man. The lead-acid batteries which powered the fuzing system remained charged for only 36 hours, after which they needed to be recharged. To do this meant disassembling

11232-402: 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

11349-498: 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

11466-446: 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

11583-438: The weaponeer in charge of the bomb. Bockscar lifted off at 03:47 on 9 August 1945, with Kokura as the primary target and Nagasaki the secondary target. The weapon was already armed but with the green electrical safety plugs still engaged. Ashworth changed them to red after ten minutes so that Sweeney could climb to 17,000 feet (5,200 m) in order to get above storm clouds. During the pre-flight inspection of Bockscar ,

11700-631: 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

11817-624: 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,

11934-501: Was assembled with just 90 bolts. On 16 July 1945, a Y-1561 model Fat Man, known as the Gadget, was detonated in a test explosion at a remote site in New Mexico , known as the " Trinity " test. It gave a yield of about 25 kilotonnes (100 TJ). Some minor changes were made to the design as a result of the Trinity test. Philip Morrison recalled that "There were some changes of importance... The fundamental thing was, of course, very much

12051-717: Was assembled with some 1,500 bolts. This was superseded by the Y-1291 design in December 1944. This redesign work was substantial, and only the Y-1222 tail design was retained. Later versions included the Y-1560, which had 72 detonators; the Y-1561, which had 32; and the Y-1562, which had 132. There were also the Y-1563 and Y-1564, which were practice bombs with no detonators at all. The final wartime Y-1561 design

12168-837: Was brought in as a consultant and discussed the problem with Neddermeyer in June 1943. Thompson was skeptical that an implosion could be made sufficiently symmetric. Oppenheimer arranged for Neddermeyer and Edwin McMillan to visit the National Defense Research Committee 's Explosives Research Laboratory near the laboratories of the Bureau of Mines in Bruceton, Pennsylvania (a Pittsburgh suburb), where they spoke to George Kistiakowsky and his team. But Neddermeyer's efforts in July and August at imploding tubes to produce cylinders tended to produce objects that resembled rocks. Neddermeyer

12285-833: Was continued, and drop tests resumed in January 1946. The Mark III Mod 0 Fat Man was ordered into production in mid-1946. High explosives were manufactured by the Salt Wells Pilot Plant , which had been established by the Manhattan Project as part of Project Camel , and a new plant was established at the Iowa Army Ammunition Plant . Mechanical components were made or procured by the Rock Island Arsenal ; electrical and mechanical components for about 50 bombs were stockpiled at Kirtland Army Air Field by August 1946, but only nine plutonium cores were available. Production of

12402-418: Was developed by von Neumann. The success of the bomb relied on absolute precision in all of the plates moving inward at the same time. To overcome the difficulty of synchronizing multiple detonations, Luis Alvarez and Lawrence Johnston invented exploding-bridgewire detonators to replace the less precise primacord detonation system. Robert Christy is credited with doing the calculations that showed how

12519-433: Was found that this was stable at room temperature when alloyed with aluminum, but aluminum emits neutrons when bombarded with alpha particles , which would exacerbate the pre-ignition problem. The metallurgists then hit upon a plutonium–gallium alloy , which stabilized the δ phase and could be hot pressed into the desired shape. They found it easier to cast hemispheres than spheres. The core consisted of two hemispheres with

12636-405: Was highly likely and that the bomb would blow itself apart during the initial formation of critical mass , creating a " fizzle ." The distance required to accelerate the plutonium to speeds where pre--detonation would be less likely would need a gun barrel too long for any existing or planned bomber. The only way to use plutonium in a workable bomb was therefore implosion. The impracticability of

12753-513: Was immediately suggested, and Kistiakowsky was brought into the project as a consultant in October. The implosion project remained a backup until April 1944, when experiments by Emilio G. Segrè and his P-5 Group at Los Alamos on the newly reactor-produced plutonium from the X-10 Graphite Reactor at Oak Ridge and the B Reactor at the Hanford Site showed that it contained impurities in

12870-413: Was live. Colonel Paul Tibbets and Sweeney therefore elected to have Bockscar continue the mission. Kokura was obscured by clouds and drifting smoke from fires started by a major firebombing raid by 224 B-29s on nearby Yahata the previous day. This covered 70% of the area over Kokura, obscuring the aiming point. Three bomb runs were made over the next 50 minutes, burning fuel and repeatedly exposing

12987-512: Was named only to contrast with the Thin Man. Los Alamos's Thin Man and Fat Man code names were adopted by the United States Army Air Forces in their involvement in the Manhattan Project, codenamed Silverplate . A cover story was devised that Silverplate was about modifying a Pullman car for use by President Franklin Roosevelt (Thin Man) and United Kingdom Prime Minister Winston Churchill (Fat Man) on

13104-562: Was nicknamed Helen of Bikini and was placed without its tail fin assembly in a steel caisson made from a submarine's conning tower; it was detonated 90 feet (27 m) beneath the landing craft USS LSM-60 . The two weapons yielded about 23 kilotonnes (96 TJ) each. The Los Alamos Laboratory and the Army Air Forces had already commenced work on improving the design. The North American B-45 Tornado , Convair XB-46 , Martin XB-48 , and Boeing B-47 Stratojet bombers had bomb bays sized to carry

13221-533: Was reportedly because: At the same time that he cancelled Duck Hook, it seems that Nixon embarked on a new strategy to start a "series of increased [nuclear] alert measures designed to convey to the Soviets an increasing readiness by U.S. strategic forces," according to Kissinger aide Alexander Haig . Nuclear weapons A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions , either fission (fission bomb) or

13338-563: Was stenciled on the bomb's nose, standing for "Joint Army-Navy-Civilian Fuckup", a play on the acronym " SNAFU ". It was then wheeled to the bomb bay of the B-29 Superfortress named Bockscar after the plane's command pilot Captain Frederick C. Bock , who flew The Great Artiste with his crew on the mission. Bockscar was flown by Major Charles W. Sweeney and his crew, with Commander Frederick L. Ashworth from Project Alberta as

13455-744: 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

13572-484: Was the only person who believed that implosion was practical, and only his enthusiasm kept the project alive. Oppenheimer brought John von Neumann to Los Alamos in September to take a fresh look at implosion. After reviewing Neddermeyer's studies, and discussing the matter with Edward Teller , von Neumann suggested the use of high explosives in shaped charges to implode a sphere, which he showed could not only result in

13689-408: Was warm to the touch, emitting 2.4 W/kg-Pu, about 15 W for the 6.19-kilogram (13.6 lb) core. The explosion symmetrically compressed the plutonium to twice its normal density before the "Urchin" added free neutrons to initiate a fission chain reaction . The result was the fission of about 1 kilogram (2.2 lb) of the 6.19 kilograms (13.6 lb) of plutonium in the pit, or about 16% of

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