The United States was the first country in the world to develop nuclear weapons, and is the only country believed to have used them as actual weapons, during the two bombings of Hiroshima and Nagasaki in World War II. Before and during the Cold War it conducted over a thousand nuclear tests and developed many long-range weapon delivery systems. It maintains an arsenal of about 5,500 warheads to this day, as well as facilities for their construction and design, though many of the Cold War facilities have since been deactivated and are sites for environmental remediation.

Development history

Manhattan Project

The United States of America first began developing nuclear weapons during World War II under the order of President Franklin Roosevelt in 1939, motivated by a fear that they were engaged in a race with Nazi Germany to develop such a weapon. After a slow start under the direction of the National Bureau of Standards, at the urging of British scientists and American administrators the program was put under the Office of Scientific Research and Development, where in 1942 it was officially transferred under the auspices of the U.S. Army and became known as the Manhattan Project. Under the direction of General Leslie Groves, over thirty different sites were constructed for the research, production, and testing of components related to bomb making. These included the scientific laboratory, Los Alamos (in New Mexico), under the direction of physicist Robert Oppenheimer, a plutonium production facility, Hanford (in Washington), and a uranium enrichment facility, Oak Ridge (in Tennessee).

By investing heavily both in breeding plutonium in early nuclear reactors, and in both the electromagnetic and gaseous diffusion enrichment processes for the production of uranium-235, the United States was able by mid-1945 to develop three usable weapons. A plutonium-implosion design weapon was tested on 16 July 1945 ("Trinity"), with around a 20 kiloton yield. On the orders of President Harry S. Truman, on 6 August of the same year a uranium-gun design bomb ("Little Boy") was used against the city of Hiroshima, Japan, and on 9 August a plutonium-implosion design bomb ("Fat Man") was used against the city of Nagasaki, Japan. The two weapons killed approximately 250,000 Japanese civilians outright, and thousands more have died over the years from radiation sickness and related cancers.

During the Cold War

Between 1945 and 1990, more than 70,000 total warheads were developed, in over 65 different varieties, ranging in yield from around .01 kilotons (such as the man-portable Davy Crockett shell) to the 25 megaton B41 bomb.

Between 1940 and 1996, the U.S. spent at least $5.8 trillion (in 1996 dollars) on nuclear weapons development. Over half of this was spent on building delivery mechanisms for the weapon. $365 billion was spent on nuclear waste management and environmental remediation.

Post-Cold War

After the end of the Cold War following the dissolution of the Soviet Union in 1991, the U.S. nuclear program was heavily curtailed, halting its program of nuclear testing, ceasing in the production of new nuclear weapons, and reducing its stockpile by half by the mid-1990s under President Bill Clinton. Many of its former nuclear facilities were shut down, and their sites became targets of extensive environmental remediation. Much of the former efforts towards the production of weapons became involved in the program of stockpile stewardship, attempting to predict the behavior of aging weapons without using full-scale nuclear testing. Increased funding also was put into anti-nuclear proliferation programs, such as helping the states of the former Soviet Union eliminate their former nuclear sites, and assist Russia in their efforts to inventory and secure their inherited nuclear stockpile. As of February 2006, over $1.2 billion were paid under the Radiation Exposure Compensation Act of 1990 to U.S. citizens exposed to nuclear hazards as a result of the U.S. nuclear weapons program, and by 1998 at least $759 million was paid to the Marshallese Islanders in compensation for their exposure to U.S. nuclear testing, and over $15 million was paid to the Japanese government following the exposure of its citizens and food supply to nuclear fallout from the 1954 "Bravo" test.

During the presidency of George W. Bush, and especially after the 11 September terrorist attacks of 2001, rumors have circulated in major news sources that the U.S. has been considering design of new nuclear weapons ("bunker-busting nukes"), and potentially the resumption of nuclear testing for reasons of stockpile stewardship, and non-nuclear missile defense has received additional funding as well. Statements by the U.S. government in 2004, however, imply that by 2012 the arsenal will drop to around 5,500 total warheads. According to recent reports, much of that reduction was already accomplished by January 2008.

Nuclear testing

Between and , the United States maintained a program of vigorous nuclear testing, with the exception of a moratorium between November 1958 and September 1961. A total of (by official count) 1,054 nuclear tests and two nuclear attacks were conducted, with over 100 of them taking place at sites in the Pacific Ocean, over 900 of them at the Nevada Test Site, and ten on miscellaneous sites in the United States (Alaska, Colorado, Mississippi, and New Mexico). Until November 1962, the vast majority of the U.S. tests were atmospheric (that is, above-ground); after the acceptance of the Partial Test Ban Treaty all testing was regulated underground, in order to prevent the dispersion of nuclear fallout.

The U.S. program of atmospheric nuclear testing exposed a number of the population to the hazards of fallout. Estimating exact numbers, and the exact consequences, of people exposed has been medically very difficult, with the exception of the high exposures of Marshallese Islanders and Japanese fisherman in the case of the "Castle Bravo" incident in 1954. A number of groups of U.S. citizens — especially farmers and inhabitants of cities downwind of the Nevada Test Site and U.S. military workers at various tests — have sued for compensation and recognition of their exposure, many successfully. The passing of the Radiation Exposure Compensation Act of 1990 allowed for a systematic filing of compensation claims in relation to testing as well as those employed at nuclear weapons facilities. As of June 2009 over $1.4 billion dollars total has been given in compensation, with over $660 million going to "downwinders".

A few notable U.S. nuclear tests include:

• The "Trinity" test on , was the first-ever test of a nuclear weapon (yield of around 20 kt).
• The Operation Crossroads series in July 1946, was the first postwar test series and one of the largest military operations in U.S. history.
• The Operation Greenhouse shots of May 1951 included the first boosted fission weapon test ("Item") and a scientific test which proved the feasibility of thermonuclear weapons ("George").
• The "Ivy Mike" shot of , was the first full test of a Teller-Ulam design "staged" hydrogen bomb, with a yield of 10 megatons. It was not a deployable weapon, however — with its full cryogenic equipment it weighed some 82 tons.
• The "Castle Bravo" shot of , was the first test of a deployable (solid fuel) thermonuclear weapon, and also (accidentally) the largest weapon ever tested by the United States (15 megatons). It was also the single largest U.S. radiological accident in connection with nuclear testing. The unanticipated yield, and a change in the weather, resulted in nuclear fallout spreading eastward onto the inhabited Rongelap and Rongerik atolls, which were soon evacuated. Many of the Marshall Islands natives have since suffered from birth defect and have received some compensation from the federal government. A Japanese fishing boat, the Fifth Lucky Dragon, also came into contact with the fallout, which caused many of the crew to grow ill; one eventually died.
• Shot "Argus I" of Operation Argus, on , was the first detonation of a nuclear weapon in outer space when a 1.7-kiloton warhead was detonated at 200 kilometers' altitude during a series of high altitude nuclear explosions.
• Shot "Frigate Bird" of Operation Dominic I on , was the only U.S. test of an operational ballistic missile with a live nuclear warhead (yield of 600 kilotons), at Christmas Island. In general, missile systems were tested without live warheads and warheads were tested separately for safety concerns. In the early 1960s, however, there mounted technical questions about how the systems would behave under combat conditions (when they were "mated", in military parlance), and this test was meant to dispel these concerns. However, the warhead had to be somewhat modified before its use, and the missile was only a SLBM (and not an ICBM), so by itself it did not satisfy all concerns.
• Shot "Sedan" of Operation Storax on (yield of 104 kilotons), was an attempt at showing the feasibility of using nuclear weapons for "civilian" and "peaceful" purposes as part of Operation Plowshare. In this instance, a 1280-feet-in-diameter and 320-feet-deep crater was created at the Nevada Test Site.

Delivery systems

The original weapons ("Little Boy" and "Fat Man") developed by the United States during the Manhattan Project were relatively large (the latter had a diameter of 5 feet) and heavy (around 5 tons each) weapons which required specially modified bomber planes to be adapted for their bombing missions against Japan, each of which could only carry one such weapon and only within a limited range. After these initial weapons, a considerable amount of money and research was conducted towards the goal of standardizing ("G.I. proofing") nuclear warheads (so that they did not require highly specialized experts to assemble them before use, as in the case with the idiosyncratic wartime devices) and miniaturization of the warheads for use in more variable delivery systems.

Through the aid of brainpower acquired through Operation Paperclip at the tail end of the European branch of World War II, the United States was able to embark on an ambitious program in rocketry. One of the first products of this was the development of rockets capable of holding nuclear warheads. The MGR-1 Honest John was the first of such weapons, developed in 1953 as a surface-to-surface missile with a 15 mile/25 kilometer maximum range. Because of their limited range, their potential use was heavily constrained (they could not, for example, threaten Moscow with an immediate strike).



Development of long-range bombers, such as the B-29 Superfortress, during World War II was continued during the Cold War period. The development of the B-52 Stratofortress in particular was able by the mid-1950s to carry a wide arsenal of nuclear bombs, each with different capabilities and potential use situations. Starting in 1946, the U.S. based its initial deterrence threat around the Strategic Air Command, which, by the late 1950s maintained a number of nuclear-armed bombers in the sky at all times, prepared to receive orders to attack the USSR whenever needed. This system was, however, tremendously expensive, both in natural resources and human resources, and raised the possibility of accidental or purposeful beginning of nuclear war, parodied famously in the 1964 film by Stanley Kubrick, Dr. Strangelove.

During the 1950s and 1960s, elaborate computerized early warning systems such as Defense Support Program were developed to detect incoming Soviet attacks and to coordinate response strategies. During this same period, intercontinental ballistic missile (ICBM) systems were developed which could deliver a nuclear payload across vast distances, allowing the U.S. to house nuclear forces capable of hitting the Soviet Union in the American Midwest. Shorter-range weapons, including small "tactical" weapons, were fielded in Europe as well, including nuclear artillery and man-portable Special Atomic Demolition Munition. The development of submarine launched ballistic missile (SLBM) systems allowed for hidden nuclear submarines to covertly launch missiles at distant targets as well, making it virtually impossible for the Soviet Union to successfully launch a first strike attack against the United States which would not guarantee a deadly response.

Improvements in warhead miniaturization in the 1970s and 1980s allowed for the development of MIRVs — missiles which could carry multiple warheads, each of which could be separately targetable. The question of whether these missiles should be based on constantly rotating train tracks (so as to avoid being easily targeted by opposing Soviet missiles) or based in heavily fortified silos (to possibly withstand a Soviet attack) was a major political controversy in the 1980s (eventually the silos won out). MIRVed systems allowed the U.S. to make the Soviet missile defense economically unfeasible, as each offensive missile would require between three and ten defensive missiles to counter.

Additional developments in weapons delivery included cruise missile systems, which allowed a plane to fire a long-distance, low-flying nuclear-tipped missile towards a target from a relatively comfortable distance. This innovation would make missile defense additionally difficult, if not impossible.



The current delivery systems of the U.S. makes virtually any part of the Earth's surface within the reach of its nuclear arsenal. Though its land-based missile systems have a maximum range of 10,000 kilometers (less than worldwide), its submarine-based forces extend its reach from a coastline 12,000 kilometers inland. Additionally, the ability to refuel long-range bombers in flight and the use of aircraft carriers extends the possible range virtually indefinitely.

Public reactions

From the public debut of nuclear weapons during the atomic bombings of Hiroshima and Nagasaki, they were a highly controversial technology among the citizens of the United States. While it appears that most Americans in the postwar period believed that they had, as claimed by the government, hastened the end of the war with Japan, even at that early period there were questions about the ethics of their use. In the immediate postwar period, much of the public debate was on the question of whether or not the U.S. should attempt to have a monopoly on the weapons — potentially encouraging a nuclear arms race — or whether or not it should relinquish them to an intergovernmental body (such as the newly created United Nations) or contribute to some other form of international control or information dispersal. According to the historian of science Spencer Weart, it was not until the development of multi-megaton hydrogen bombs in the 1950s that a belief that nuclear weapons could potentially end all life on the planet (especially through means of nuclear fallout, highlighted by the "Castle Bravo" accident) became common in American thought or cultural expression. For the most part, however, the vast majority of American citizens believed during this time that nuclear weapons were necessary in order to ward off the threat from the Soviet Union.



During the 1960s, following the rise of political activism in the civil rights movement, the controversy over the Vietnam War, and the beginnings of the environmentalism movement, public anxiety related to nuclear weapons began to rise to the point of direct protest. While there is little evidence that these sentiments were felt or expressed by any more than a minority of the U.S. population, their expression became increasingly amplified, especially in relation to the health hazards of nuclear testing. After the cessation of American atmospheric nuclear testing, however, the sentiment against nuclear weapons in general lost much of its momentum. During the period of détente in the 1970s, marked by weapons reduction and restriction treaties between the U.S. and the USSR, much of the anxiety over nuclear weapons in the populace and activists was transferred towards protesting civilian nuclear power plants, according to Spencer Weart's analysis.

During the presidency of Ronald Reagan in the 1980s, public anti-nuclear weapons sentiment reached its highest point, spurred by the administration's strong anti-Soviet rhetoric, Strategic Defense Initiative, and apparent reinvigoration of the arms race. Again, however, the majority of the American populace generally felt the weapons were required for U.S. national security, even though they increasingly became the flashpoints of political controversies and concern. Anti-nuclear activists shifted to a strategy of describing in detail the results of a potential nuclear attack on the United States, and a number of prominent anti-nuclear films were developed during this period, typified by the controversial The Day After in 1983.

With the fall of the Soviet Union in 1991 and the cessation of the arms race, U.S. public attitudes towards nuclear weapons became less polarized on the whole. Following the 9/11 attacks of 2001, however, concerns over whether the U.S. should develop new weapons have reinvigorated some of the older debates over their practicality, morality, and danger. The debate over the ethical implications of the bombing of Hiroshima and Nagasaki, begun in private amongst scientists and statesmen during the war, has continued to this day, in the general public as well as amongst historians, military experts, and other scholars.

Accidents

The United States nuclear program has, since its inception, suffered from a number of accidents of varying forms, ranging from single-casualty research experiments (such as that of Louis Slotin during the Manhattan Project), to the nuclear fallout dispersion of the "Castle Bravo" shot in 1954, to the accidental dropping of nuclear weapons from aircraft ("broken arrow"). How close any of these accidents came to being "major" nuclear disasters is a matter of technical and scholarly debate and interpretation.

Weapons accidentally dropped by the United States include incidents near Atlantic City, New Jersey (1957), Savannah, Georgia (1958) (see Tybee Bomb), Goldsboro, North Carolina (1961), off the coast of Okinawa (1965), in the sea near Palomares, Spain (1966, see 1966 Palomares B-52 crash), and near Thule Air Base, Greenland (1968) (see 1968 Thule Air Base B-52 crash). In some of these cases (such as Palomares), the explosive system of the fission weapon discharged, but did not trigger a nuclear chain reaction (safety features prevent this from easily happening), but did disperse hazardous nuclear materials across wide areas, necessitating expensive cleanup endeavors. Eleven American nuclear warheads are thought to be lost and unrecovered, primarily in submarine accidents.

The nuclear testing program resulted in a number of cases of fallout dispersion onto populated areas. The most significant of these was the Castle Bravo test, which spread radioactive ash over an area of over one hundred miles, including a number of populated islands. The populations of the islands were evacuated but not before suffering radiation burns. They would later suffer long-term effects, such as birth defects and increased cancer risk. There were also instances during the nuclear testing program in which soldiers were exposed to overly high levels of radiation, which grew into a major scandal in the 1970s and 1980s, as many soldiers later suffered from what were claimed to be diseases caused by their exposures.

Many of the former nuclear facilities (see next section) produced significant environmental damages during their years of activity, and since the 1990s have been Superfund sites of cleanup and environmental remediation. The Radiation Exposure Compensation Act of 1990 allows for U.S. citizens exposed to radiation or other health risks through the U.S. nuclear program to file for compensation and damages.

Development agencies

The initial U.S. nuclear program was run by the National Bureau of Standards starting in 1939 under the edict of President Franklin Delano Roosevelt. Its primary purpose was to delegate research and dispense of funds. In 1940 the National Defense Research Committee (NDRC) was established, coordinating work under the Committee on Uranium among its other wartime efforts. In June 1941, the Office of Scientific Research and Development (OSRD) was established, with the NDRC as one of its subordinate agencies, which enlarged and renamed the Uranium Committee as the Section on Uranium. In 1941, NDRC research was placed under direct control of Vannevar Bush as the OSRD S-1 Section, which attempted to increase the pace of weapons research. In June 1942, the U.S. Army Corps of Engineers took over the project to develop atomic weapons, while the OSRD retained responsibility for scientific research.

This was the beginning of the Manhattan Project, run as the Manhattan Engineering District (MED), an agency under military control which was in charge of developing the first atomic weapons. After World War II, the MED maintained control over the U.S. arsenal and production facilities and coordinated the Operation Crossroads tests. In 1946 after a long and protracted debate, the Atomic Energy Act was passed, creating the Atomic Energy Commission (AEC) as a civilian agency which would be in charge of the production of nuclear weapons and research facilities, funded through Congress, with oversight provided by the Joint Committee on Atomic Energy. The AEC was given vast powers of control over secrecy, research, and money, and could seize lands with suspected uranium deposits. Along with its duties towards the production and regulation of nuclear weapons, it additionally was in charge of stimulating development in civilian nuclear power while also regulating its safety uses. The full transference of activities was finalized in January 1947.

In 1975, following the "energy crisis" of the early 1970s and public and congressional discontent with the AEC (in part because of the impossibility to be both a producer and a regulator), it was disassembled into component parts as the Energy Research and Development Administration (ERDA), which assumed most of the AEC's former production, coordination, and research roles, and the Nuclear Regulatory Commission, which assumed its civilian regulation activities.

ERDA was short-lived, however, and in 1977 the U.S. nuclear weapons activities were reorganized under the Department of Energy, which currently maintains such responsibilities through the semi-autonomous National Nuclear Security Administration today. Some functions have also been taken over or shared by the Department of Homeland Security in 2002. The already-built weapons themselves are in the control of the Strategic Command, which is part of the Department of Defense.

In general, these agencies served to coordinate research and build sites. They generally operated their sites through contractors, however, both private and public (for example, Union Carbide, a private company, ran Oak Ridge National Laboratory for many decades; the University of California, a public educational institution, has run the Los Alamos and Lawrence Livermore laboratories since their inception, and will joint-manage Los Alamos with the private company Bechtel as of its next contract). Funding was received both through these agencies directly, but also from additional outside agencies, such as the Department of Defense. Each branch of the military also maintained its own nuclear-related research agencies (generally related to delivery systems).

Weapons production complex

This table is not comprehensive, as numerous facilities throughout the United States have contributed to its nuclear weapons program. It includes the major sites related primarily to the U.S. weapons program (past and present), their basic site functions, and their current status of activity. Not listed are the many bases and facilities at which nuclear weapons have been deployed. In addition to deploying weapons on its own soil, during the Cold War the United States also stationed nuclear weapons in 27 foreign countries and territories, including Okinawa, Japan (during the occupation immediately following WWII)), Greenland, Germany, Taiwan, and Morocco.

Site name	Location	Function	Status
Los Alamos National Laboratory	Los Alamos, New Mexico	Research, Design, Pit Production	Active
Lawrence Livermore National Laboratory	Livermore, California	Research and design	Active
Sandia National Laboratories	Livermore, California; Albuquerque, New Mexico	Research and design	Active
Hanford Site	Richland, Washington	Material production (Plutonium)	Not active, remediation
Oak Ridge National Laboratory	Oak Ridge, Tennessee	Material production (Uranium-235, fusion fuel), research	Active to some extent
Y-12 National Security Complex	Oak Ridge, Tennessee	Component fabrication, stockpile stewardship, uranium storage	Active
Nevada Test Site	Near Las Vegas, Nevada	Nuclear testing and nuclear waste disposal	No nuclear tests since 1992, engaged in waste disposal
Yucca Mountain	Nevada Test Site	Waste disposal (primarily power reactor)	Pending
Waste Isolation Pilot Plant	East of Carlsbad, New Mexico	Radioactive waste from nuclear weapons production	Active
Pacific Proving Grounds	Marshall Islands	Nuclear testing	Not active, last test in 1962
Rocky Flats Plant	Near Denver, Colorado	Components fabrication	Not active, remediation
Pantex	Amarillo, Texas	Weapons assembly, disassembly, pit storage	Active, esp. disassembly
Fernald Site	Near Cincinnati, Ohio	Material fabrication (Uranium-235)	Not active, remediation
Paducah Plant	Paducah, Kentucky	Material production (Uranium-235)	Active (commercial use)
Portsmouth Plant	Near Portsmouth, Ohio	Material fabrication (Uranium-235)	Active, (centrifuge), but not for weapons production
Kansas City Plant	Kansas City, Missouri	Component production	Active
Mound Plant	Miamisburg, Ohio	Research, component production, Tritium purification	Not active, remediation
Pinellas Plant	Largo, Florida	Manufacture of electrical components	Active, but not for weapons production
Savannah River Site	Near Aiken, South Carolina	Material production (Plutonium, Tritium)	Active (limited operation), remediation

Proliferation

Early on in the development of its nuclear weapons, the United States relied in part on information-sharing with both the United Kingdom and Canada, as codified in the Quebec Agreement of 1943. These three parties agreed not to share nuclear weapons information with other countries without the consent of the others, an early attempt at nonproliferation. After the development of the first nuclear weapons during World War II, though, there was much debate within the political circles and public sphere of the United States about whether or not the country should attempt to maintain a monopoly on nuclear technology, or whether it should undertake a program of information sharing with other nations (especially its former ally and likely competitor, the Soviet Union), or submit control of its weapons to some sort of international organization (such as the United Nations) who would use them to attempt to maintain world peace. Though fear of a nuclear arms race spurred many politicians and scientists to advocate some degree of international control or sharing of nuclear weapons and information, many politicians and members of the military believed that it was better in the short term to maintain high standards of nuclear secrecy and to forestall a Soviet bomb as long as possible (and they did not believe the USSR would actually submit to international controls in good faith).



Since this path was chosen, the United States was, in its early days, essentially an advocate for the prevention of nuclear proliferation, though primarily for the reason originally of self-preservation. A few years after the USSR detonated its first weapon in 1949, though, the U.S. under President Dwight D. Eisenhower sought to encourage a program of sharing nuclear information related to civilian nuclear power and nuclear physics in general. The Atoms for Peace program, begun in 1953, was also in part political: the U.S. was better poised to commit various scarce resources, such as enriched uranium, towards this peaceful effort, and to request a similar contribution from the Soviet Union, who had far fewer resources along these lines; thus the program had a strategic justification as well, as was later revealed by internal memos. This overall goal of promoting civilian use of nuclear energy in other countries, while also preventing weapons dissemination, has been labeled by many critics as contradictory and having led to lax standards for a number of decades which allowed a number of other nations, such as India, to profit from dual-use technology (purchased from other nations other than the U.S.).

The United States is one of the five "nuclear weapons states" permitted to maintain a nuclear arsenal under the Nuclear Non-Proliferation Treaty, of which it was an original signatory on 1 July 1968 (ratified 5 March 1970).

The Cooperative Threat Reduction program of the Defense Threat Reduction Agency was established after the breakup of the Soviet Union in 1991 to aid former Soviet bloc countries in the inventory and destruction of their sites for developing nuclear, chemical, and biological weapons, and their methods of delivering them (ICBM silos, long range bombers, etc.). Over $4.4 billion has been spent on this endeavor to prevent purposeful or accidental proliferation of weapons from the former Soviet arsenal.

After India and Pakistan tested nuclear weapons in 1998, President Bill Clinton imposed economic sanctions on the countries. In 1999, however, the sanctions against India were lifted; those against Pakistan were kept in place as a result of the military government which had taken over. Shortly after the September 11 attacks in 2001, President George W. Bush lifted the sanctions against Pakistan as well, in order to get the Pakistani government's help as a conduit for US and NATO forces for operations in Afghanistan.

The U.S. government has officially taken a silent policy towards the nuclear weapons ambitions of the state of Israel, while being exceedingly vocal against proliferation of such weapons in the countries of Iran and North Korea, something which has been called hypocritical by many critics. The same critics point out the fact that it is violating its own non-proliferation treaties in the pursuit of so-called "nuclear bunker busters". The 2003 invasion of Iraq by the U.S. was done, in part, on accusations of weapons development, and the Bush administration has said that its policies on proliferation were responsible for the Libyan government's agreement to abandon its nuclear ambitions.

International relations and nuclear weapons

In 1958, the United States Air Force had considered a plan to drop nuclear bombs on China during a confrontation over Taiwan but it was overruled, previously secret documents showed after they were declassified due to the Freedom of Information Act in April 2008. The plan included an initial plan to drop 10-15 kiloton bombs on airfields in Amoy (now called Xiamen) in the event of a Chinese blockade against Taiwan's so-called Offshore Islands.

Current status

The United States is one of the five recognized nuclear powers under the Nuclear Non-Proliferation Treaty ("NPT"). It maintains a current arsenal of around 9,960 intact warheads, of which 5,735 are considered active or operational, and of these only a certain number are deployed at any given time. These break down into 5,021 "strategic" warheads, 1,050 of which are deployed on land-based missile systems (all on Minuteman ICBMs), 1,955 on bombers (B-52, B-1B, and B-2), and 2,016 on submarines (Ohio class), according to a 2006 report by the Natural Resources Defense Council. Of 500 "tactical" "nonstrategic" weapons, around 100 are Tomahawk cruise missiles and 400 are B61 bomb. A few hundred of the B61 bombs are located at seven bases in six European NATO countries (Belgium, Germany, Italy, the Netherlands, Turkey and the United Kingdom), the only such weapons in forward deployment.

Around 4,225 warheads have been removed from deployment but have remained stockpiled as a "responsible reserve force" on inactive status. Under the May 2002 Treaty on Strategic Offensive Reductions ("SORT"), the U.S. pledged to reduce its stockpile to 2,200 operationally deployed warheads by 2012, and in June 2004 the Department of Energy announced that "almost half" of these warheads would be retired or dismantled by then.

The future nuclear stockpile under SORT will be based on:

• 450 Minuteman-III ICBM with 500 warheads. 400 with a single warhead and 50 with 2 MIRVs. There will be 200 W78 warheads and 300 W87 warheads.
• 12 operational Ohio-class submarines with another 2 in overhaul. Each has 24 Trident-II missiles with 4 MIRV warheads of the W76 and W88 warheads, that will be a total of 1152 warheads. There will be 384 W88 and 768 W76 warheads for submarines.
• 94 B-52 and 20 B-2 strategic bombers with 540 warheads of the AGM-86 and B61 and B83. There will be 528 nuclear AGM-86B cruise Missiles with 300 active and 228 in reserve. Along with the 528 ALCM there will be 120 B61-7, 20 B61-11 and 100 B83 nuclear bombs for the bomber fleet.

The SORT treaty does not make the U.S. reduce its tactical nuclear arsenal so there will be 500-800 active tactical nuclear weapons. Also the weapons taken from active states do not have to be destroyed so there will be at least 2400 responsive reserve warheads.

A 2001 nuclear posture review published by the Bush administration called for a reduction in the amount of time needed to test a nuclear weapon, and for discussion on possible development in new nuclear weapons of a low-yield, "bunker-busting" design (the Robust Nuclear Earth Penetrator). Work on such a design had been banned by Congress in 1994, but the banning law was repealed in 2003 at the request of the Department of Defense. The Air Force Research Laboratory researched the concept, but the United States Congress canceled funding for the project in October 2005 at the National Nuclear Security Administration's request. According to Fred T. Jane's Information Group, the program may still continue under a new name.

In 2006, the Bush administration also proposed the Reliable Replacement Warhead program, which is now in the process of design and development, to develop an entirely-new family of nuclear ICBMs. The program, intended to produce a simple, reliable, long-lasting, and low-maintenance future nuclear force for the United States, has encountered opposition due to the obligations of the United States under Article VI of the Nuclear Non-Proliferation Treaty, which the United States has signed, ratified, and is bound by, and which obligates the five nuclear weapons states who are bound by it (of which the United States is such a state) to work in good faith towards nuclear disarmament.

The Reliable Replacement Warhead is designed to replace the aging W76 warhead currently in a life-extension program. It will incorporate a well-tested and verified primary SKUA9 and a new fusion secondary. The device will be built much much more robustly than its predecessors and should require longer periods between service and replacement. It will use insensitive high explosives, which are virtually impossible to detonate without the right mechanism. The new insensitive explosives can hit a concrete wall at Mach 4 and still not detonate. The device will also use a heavy radiation case for reliability. Since this weapon will supposedly never be tested via detonation, as has every weapon presently in the US arsenal, some fear that either the weapon will not be reliable, or will require testing to confirm its reliability, breaking the moratorium that has been observed by the recognized nuclear powers (the recognized nuclear powers include the US, Russia, the UK, the PRC, and France; they do not include the generally-recognized but undeclared Israel, nor the declared but unrecognized India, Pakistan, and North Korea) and was disliked by several elements of the Bush Administration, who believed nuclear tests ought to be conducted routinely; indeed, the Reliable Replacement Warhead is seen as the first step in the implementation of the US nuclear weapons laboratories' plan, called "Complex 2030", to rebuild dismantled nuclear weapons infrastructure so as to ensure that nuclear weapon design continues to be a field of research in the US through the mid-point of the 21st century.

In 2005 the U.S. revised its declared nuclear political strategy, the Doctrine for Joint Nuclear Operations, to emphasize the possibility of the use of nuclear weapons preemptively against an adversary possessing weapons of mass destruction or overwhelming conventional forces. Whether the Single Integrated Operational Plan ("SIOP") has been revised accordingly is uncertain, but possible.

On April 3 2009, U.S. president Barack Obama announced that he would outline details of a goal of "a world without nuclear weapons". To that goal, U.S. President Barack Obama and Russian President Dmitry Medvedev signed a preliminary agreement on July 6, 2009, to reduce the number of active nuclear weapons to between 1,500 and 1,675 from 2,200. The new caps on nuclear arsenals would need to be fully implemented by 2012.

See also

• United States and weapons of mass destruction
• History of nuclear weapons
• National Security Strategy of the United States
• United States Strategic Command
• List of nuclear tests
• Nuclear-free zone
• Global Security Institute
• Anti-nuclear movement in the United States

Notes

1. According to Carey Sublette's Nuclear Weapon Archive, the United States "conducted (by official count) 1054 nuclear tests" between 1945 and 1992.
2. Brookings Institution, "50 Facts About Nuclear Weapons", at http://www.brook.edu/FP/PROJECTS/NUCWCOST/50.HTM
3. Brookings Institution, "Estimated Minimum Incurred Costs of U.S. Nuclear Weapons Programs, 1940-1996", at http://www.brook.edu/fp/projects/nucwcost/figure1.htm
4. "Radiation Exposure Compensation System Claims to Date Summary of Claims Received", updated regularly at http://www.usdoj.gov/civil/omp/omi/Tre_SysClaimsToDateSum.pdf
5. Carey Sublette, "Gallery of U.S. Nuclear Tests", online at http://nuclearweaponarchive.org/Usa/Tests/
6. Radiation Exposure Compensation System: Claims to Date Summary of Claims Received by 06/11/2009
7. [1]

References

• Hacker, Barton C. Elements of Controversy: The Atomic Energy Commission and Radiation Safety in Nuclear Weapons Testing, 1947-1974. Berkeley, CA: University of California Press, 1994. ISBN 0-520-08323-7
• Hansen, Chuck. U.S. Nuclear Weapons: The Secret History. Arlington, TX: Aerofax, 1988. ISBN 0-517-56740-7
• MacKenzie, Donald A. Inventing Accuracy: A Historical Sociology of Nuclear Missile Guidance. Cambridge, MA: MIT Press, 1990. ISBN 0-262-13258-3
• Schwartz, Stephen I. Atomic Audit: The Costs and Consequences of U.S. Nuclear Weapons. Washington, D.C.: Brookings Institution Press, 1998. [149570] ISBN 0-8157-7773-6
• Weart, Spencer R. Nuclear Fear: A History of Images. Cambridge, MA: Harvard University Press, 1985. ISBN 0-674-62835-7
• Biello,David."A Need for New Warheads?" Scientific American, November 2007

External links

• Video archive of US Nuclear Testing at sonicbomb.com
• U.S. Nuclear Forces 2006 Robert S. Norris and Hans M. Kristensen Bulletin of the Atomic Scientists, January/February 2006
• Nuclear Threat Initiative: United States
• NDRC's data on the US Nuclear Stockpile, 1945-2002
• GlobalSecurity.org, esp. facilities, forces, and operations
• Nuclear Weapons Archive, esp. nuclear tests and U.S. Arsenal, Past and Present
• US Doctrine for Joint Nuclear Operations
• Comment matrix on Doctrine for Joint Nuclear Operations
• Snapshot of the U.S. Nuclear Weapons Complex, April 2004 by the Los Alamos Study Group
• 20 Mishaps That Might Have Started Accidental Nuclear War A somewhat chilling list of the closest calls so far.
• US Nuclear Weapons Accidents list published by the Center for Defense Information ( CDI)
• Putin: U.S. pushing others into nuclear ambitions (February 2007)
• New nuclear warhead design for US
• U.S. government settles on design for new nuclear warheads
• Annotated bibliography of U. S. nuclear weapons programs from the Alsos Digital Library for Nuclear Issues
• US announces plans to build new nuclear warheads
• Trends in U.S. Nuclear Policy - analysis by William C. Potter, IFRI Proliferation Papers n°11, 2005