Country Profiles: United States

US flag NPT: 1970
CTBT: 1996 (signed but not ratified)
First Test: 1945
First Hydrogen Bomb: 1952

Current number of nuclear warheads:
Strategic: 7206
Tactical: 1670
Total: 8876

Last Updated: 2/27/02

The United States began research into an atomic bomb in 1939, when President Roosevelt first became aware of the research to that end going on in Germany. In 1942, a secret program to develop the bomb, the Manhattan Project, got underway, and several nuclear installations were built across the country during the next several years. On July 16, 1945, the United States exploded the world’s first nuclear device at Alamogordo, New Mexico. Less than a month later, on August 6, the United States dropped a nuclear bomb on Hiroshima, and another on Nagasaki on August 9. The reasons for dropping the bomb were varied and are still debated to this day. American leaders were anxious to end the war in the Pacific theater as quickly as possible. Japan had ignored a request for surrender issued on July 26 (the Potsdam declaration). After the devastation wrought by the two bombs, Japanese leaders requested surrender under the terms of the Potsdam declaration on August 10, and finally surrendered on August 14. Despite much talk about securing ‘unconditional surrender,’ the Japanese were allowed some concessions, such as retaining their emperor. It is probable, however, that dropping the bomb was meant to impress not only the Japanese, but also the Soviets. Ending the war quickly would prevent the Soviet army from invading Japan and would also assert American technological dominance at the start of the nascent Cold War.

Immediately after the war there was some sentiment in the United States that nuclear technology should be shared internationally. The Acheson-Lilienthal plan was meant to achieve that goal, but it was presented in a revised and contentious form in the United Nations, and the Soviet Union rejected it. Although they offered a counterproposal, the Gromyko plan, the negotiations fell through, and the Cold War soon became the focus of the American nuclear weapons program. However, after 1946, nuclear technology was officially placed under civilian control in the United States, although the military would continue to play a central role.

In 1948, the Soviet Union blocked Berlin, cutting West Berlin (which, though located in East Germany, was under Western control) off from West Germany. The crisis lasted until May 1948, and the United States kept up a vast airlift of supply and food the entire time. In part as a result of this incident, the United States decided to place nuclear weapons in Europe as a way to curb Stalin’s potentially expansionist plans. The idea was to create a nuclear tripwire that would deter a Soviet invasion.

The arms race between the United States and the Soviet Union accelerated in 1950 when President Harry Truman ordered the development of a hydrogen bomb. The decision was made in response both to the detonation of the first Soviet atomic bomb the previous summer and the warnings of American scientists of the danger of allowing the Soviet Union to develop a hydrogen bomb first. The US detonated the first hydrogen bomb on November 1, 1952.

The early Cold War years were also a time when the United States struggled to find a strategic role for nuclear weapons. Less than six months after the start of the Korean War, in December 1950, General Douglas MacArthur requested discretionary authority to use atomic weapons during the conflicts. Although Truman did not allow general use of atomic weapons during the conflict, he did authorize use of atomic weapons if large numbers of Chinese troops had joined the war or if bombers were launched against United Nations forces from Manchurian bases. The weapons were not used in this conflict, but nuclear-armed bombers were stationed in Japan after the war as part of a general operation to contain Communism in East Asia.

The Eisenhower administration remained ambiguous about the role of nuclear weapons. President Dwight Eisenhower initiated the Atoms for Peace program less than a year after his election, calling for peaceful nuclear technology to be extended to many countries in order “to strip nuclear energy of its military casing and adapt it to the arts of peace.” However, Eisenhower and Secretary of State John Foster Dulles extended the theoretical use of nuclear weapons in significant ways. The administration worked on developing a coordinated nuclear war plan, eventually producing in 1960 the SIOP 62, which called for more than 3,000 nuclear weapons to be launched against 1,000 targets in the first few hours of a potential conflict with Russia. In January 1954, Dulles announced the policy of “massive retaliation,” which was meant to replace large-scale conventional involvements with deterrence through the threat of a huge, probably nuclear, response. Eisenhower made an offer of two atomic bombs to the French to use in Indochina, which France declined. In 1955, during a debate over whether to use atomic weapons in the Quemoy-Matsu dispute with China, Eisenhower publicly commented that “A-bombs can be used … as you would use a bullet.” In another dispute over the islands in 1958, however, Eisenhower refused a request by the Joint Chiefs of Staff to order nuclear strikes against China.

A number of significant technological milestones were achieved in this period, including the first nuclear submarine (launched in January 1954), the first underground tests (carried out in the Nevada desert in 1957), and the first intercontinental ballistic missile (the Atlas D, launched in October 1959).

The administration of President John F. Kennedy began in a contradictory way. On September 20, 1961, the United States and the Soviet Union signed a joint statement that outlined a program for nuclear disarmament. The same month, both nations broke the moratorium on testing that had lasted since 1958.

The Cuban Missile Crisis brought nuclear tensions to a head. The Bay of Pigs debacle of April 1961 put the island in the Cold War spotlight, and in October 1962 a U-2 reconnaissance flight discovered Soviet missile installations there. The revelation led to a tense standoff between the United States and the Soviet Union, as the United States blockaded Cuba and put its military on high alert. It was unclear whether Soviet and Cuban officers had the authority to use the missiles or tactical nuclear weapons against the United States in case of attack. After thirteen days, the situation was defused when Kennedy and Khrushchev reached a compromise whereby the Soviet missiles would be publicly withdrawn from Cuba while American missiles would be secretly withdrawn from Turkey six months later, allowing both sides to save face.

In 1963, the United States and the Soviet Union established a hot line between their two governments in order to facilitate the sort of communication that had led to the resolution of the Cuban Missile Crisis and also to help prevent potential accidents and misunderstandings. Kennedy also declared a unilateral moratorium on atmospheric testing in June, which helped pave the way for the Partial Test Ban Treaty, which entered into force in October of that year.

In the late 1960s and early 1970s the United States was focused in large part on the Vietnam War, a war which demonstrated the real strategic limitations of nuclear weapons, since the United States’ vast nuclear arsenal failed to prevent its inability to overcome the small, technologically unsophisticated Vietnamese forces. During this period the United States pursued arms control talks while continuing to develop its nuclear arsenal. In 1968, the United States signed the Nuclear Non-Proliferation Treaty as a nuclear weapons state, thus promising to move toward nuclear disarmament. In April 1970, the main round of the Strategic Arms Limitation Talks (SALT) took place, leading in 1972 to the Anti-Ballistic Missile (ABM) Treaty, the SALT accord, and the Interim Agreement on Strategic Offensive Arms signed by Nixon and Brezhnev. The two nations also agreed to a threshold test ban treaty in 1974 and a treaty limiting underground nuclear explosions for peaceful purposes in 1976. On the other hand, in August 1970, the United States deployed the first missile with Multiple Independently targetable Reentry Vehicles (MIRVs), and in 1977 it tested a neutron bomb (designed for use against humans in the battlefield), though it abandoned development of that bomb the next year.

The generally cooperative tenor of the Carter administration frayed in 1979 when the Soviet Union invaded Afghanistan. Carter withdrew the SALT II treaty from consideration by the Senate for ratification, requested an increase in defense spending, and signed Presidential Directive 59, which called on the United States to develop and maintain the capability to wage a protracted nuclear war.

Reagan embarked on a large defense buildup during the 1980s. He deployed Pershing II nuclear missiles in Germany in 1983. The same year, Reagan delivered his “Star Wars” speech that called for a missile defense system. The system would be based in space and would protect the United States from intercontinental ballistic missiles using a variety of technologies, including space-based lasers and small autonomous satellites dubbed ‘Brilliant Pebbles’.

The missile defense proposal was a major sticking point in the 1986 Reykjavik talks between Reagan and Gorbachev on the feasibility of the abolition of nuclear weapons. However, significant disarmament strides were taken in the late 1980s and early 1990s. The United States and the Soviet Union agreed to scrap their intermediate-range nuclear forces in December 1987, and Bush and Gorbachev signed the first Strategic Arms Reduction Treaty (START I) in 1991. The same year, Bush cancelled the MX rail-garrison and short-range attack missile programs. He withdrew all the remaining Army ground-based tactical nuclear weapons and Navy tactical weapons and ended the twenty-four-hour alert status of B-1B and B-52 bombers. The next year, Bush cancelled the Midgetman Missile Program, ended further production of W-88 warheads and MX2 test missiles, and capped the B-2 bomber program at 20 planes and the advanced cruise missiles at 640 missiles. The Senate voted for a nine-month moratorium on nuclear weapons testing beginning October 2, 1992, and a final cut-off of all testing by September 30, 1996.

In his last days in office, Bush signed START II with Yeltsin, though this treaty is stalled in the United States Senate.

The Senate rejected ratification of the Comprehensive Test Ban Treaty in October 1999 after a brief period of debate. Fear that it would be impossible to prevent other nations from conducting clandestine tests and concern that tests would prove necessary to maintain the United States nuclear arsenal proved decisive factors. The rejection has prevented further progress on the treaty, which must be ratified by 44 nuclear capable states, including the United States, in order to enter into effect.

The United States has produced a total of 70,000 nuclear weapons of seventy-one major types over the course of the past half-century. Its current arsenal remains central to its military posture. Below is a summary of its current arsenal.

Designation Warhead Type Yield (Kilotons) Number First Produced
B53 Mod-1 Bomb-Strategic 9000 50 8/62




W62/Mk-12 Ballistic Missile Warhead/RV 170 610 3/70
W76/Mk-4 Ballistic Missile
100 3000 6/78
W78/Mk-12a Ballistic Missile Warhead/RV 335 920 8/79
   Mod 0
   Mod 1
   Mod 1
Cruise Missile
Sea Launched
Air Launched
Air Launched
B83 Bomb-Strategic Low to 1200 650 6/83
W87/Mk-21 Ballistic Missile Warhead/RV 300
(upgradeable to 475)
525 4/86
W88/Mk-5 Ballistic Missile Warhead/RV 475 400 9/88
W84 (inactive) Cruise Missile Warhead .3/?/150 350 6/83