United States and Weapons of Mass Destruction - Nuclear Weapons

Nuclear Weapons

Nuclear weapons have been deployed twice in wartime: two nuclear weapons were used by the United States against Japan in World War II in the atomic bombings of Hiroshima and Nagasaki. Altogether, the two bombings killed an estimated 200,000 Japanese citizens and injured another 130,000.

The U.S. conducted an extensive nuclear testing program. 1,054 tests were conducted between 1945 and 1992. The exact number of nuclear devices detonated is unclear because some tests involved multiple devices while a few failed to explode or were designed not to create a nuclear explosion. The last nuclear test by the United States was on September 23, 1992; the U.S. has signed but not ratified the Comprehensive Test Ban Treaty.

Currently, the United States nuclear arsenal is deployed in three areas:

• Land-based intercontinental ballistic missiles, or ICBMs;
• Sea-based, nuclear submarine-launched ballistic missiles, or SLBMs; and
• Air-based nuclear weapons of the U.S. Air Force's heavy bomber group

The United States is one of the five "Nuclear Weapons States" under the Nuclear Non-Proliferation Treaty, which the US ratified in 1968. On October 13, 1999, the U.S. Senate rejected ratification of the Comprehensive Test Ban Treaty, having previously ratified the Partial Test Ban Treaty in 1963. The U.S. has not, however, tested a nuclear weapon since 1992, though it has tested many non-nuclear components and has developed powerful supercomputers in an attempt to duplicate the knowledge gained from testing without the actual tests themselves.

In the early 1990s, the U.S. stopped developing new nuclear weapons and now devotes most of its nuclear efforts into stockpile stewardship, maintaining and dismantling its now-aging arsenal. The administration of George W. Bush decided in 2003 to engage in research towards a new generation of small nuclear weapons, especially "earth penetrators" . The budget passed by the United States Congress in 2004 eliminated funding for some of this research including the "bunker-busting or earth-penetrating" weapons.

The exact number of nuclear weapons possessed by the United States is difficult to determine. Different treaties and organizations have different criteria for reporting nuclear weapons, especially those held in reserve, and those being dismantled or rebuilt:

• As of 1999, the U.S. was said to have 12,000 nuclear weapons of all types stockpiled.
• In its Strategic Arms Reduction Treaty (START) declaration for 2003, the U.S. listed 5968 deployed warheads as defined by START rules.
• For 2007, the Bulletin of the Atomic Scientists listed the U.S. with about 5,400 total nuclear warheads: around 3,575 strategic and 500 nonstrategic warheads; and about 1,260 additional warheads held in the inactive stockpile. Other warheads are in some step of the disassembly process.
• The exact number as of Sept. 30, 2009, was 5,113 warheads, according to a U.S. fact sheet released May 3, 2010.

In 2002, the United States and Russia agreed in the SORT treaty to reduce their deployed stockpiles to not more than 2,200 warheads each. In 2003, the US rejected Russian proposals to further reduce both nation's nuclear stockpiles to 1,500 each. In 2007, for the first time in 15 years, the United States built some new warheads. These were to replace some older warheads as part of the Minuteman III upgrade program. 2007 also saw the first Minuteman III missiles removed from service as part of the drawdown. Overall, stockpiles and deployment systems continue to decline in number under the terms of the New START treaty.

In 2010, The Pentagon disclosed that the current size of its nuclear arsenal is a total of 5,113 warheads operationally deployed, kept in active reserve and held in inactive storage. The figure does not include the estimated 4,600 warheads that have been retired and scheduled for dismantlement. The number of operationally deployed strategic warheads stands at 1,968.