US nuclear arsenal (click image to enlarge)

For the first time, the United States has formally disclosed the current size of its nuclear stockpile–5113 weapons as of 30 September 2009 (Anne Gearan, “U.S. comes clean on size of nuclear stockpile: 5,113,” Associated Press, 3 May 2010).

U.S. Secretary of State Hillary Clinton revealed the number, and provided figures for previous years, on the opening day of the Non-Proliferation Treaty’s 8th Review Conference, which is taking place in New York from 3 May until 28 May.

The disclosure was incomplete in that it did not include the number of retired weapons awaiting dismantlement held by the U.S. Adding that number, estimated by the Federation of American Scientists to be about 4500, makes the total number of nuclear weapons possessed by the U.S. about 9,600. Only the Russian nuclear arsenal is larger.

The U.S. also failed to reveal the explosive power, or “yield”, of its stockpile, which despite significant reductions since the end of the Cold War could still be as much as 100,000 times that of the weapon dropped on Hiroshima.

Nonetheless, the U.S. disclosure is a major step forward for nuclear transparency, and it raises the bar considerably for the other nuclear-weapon states, which to date have not revealed nearly as much information about their own arsenals.

Further commentary

Hans M. Kristensen, “United States Discloses Size of Nuclear Weapons Stockpile,” FAS Strategic Security Blog, 3 May 2010