NRDC: Nuclear Notebook
Global nuclear stockpiles, 1945-2006 http://www.thebulletin.org/article_nn.php?art_ofn=ja06norris
By Robert S. Norris and Hans M. Kristensen July/August 2006 pp. 64-66 (vol. 62, no. 4) ) © 2006 Bulletin of the Atomic Scientists
Excessive secrecy prohibits the public from knowing the exact number of nuclear weapons in the world. Each nation shields the details of its own nuclear arsenal and generally knows few precise details about the size and composition of other countries' stockpiles.
Despite the uncertainty, we know that the total global nuclear weapons stockpile is considerably smaller than the 1986 Cold War high of 70,000-plus warheads. Through a series of arms control agreements and unilateral decisions, nuclear weapon states have reduced the global stockpile to its lowest level in 45 years. In the same period, the number of nuclear weapon states has grown from three to nine.
We estimate that these nine states possess about 27,000 intact nuclear warheads, of which 97 percent are in U.S. and Russian stockpiles. About 12,500 of these warheads are considered operational, with the balance in reserve or retired and awaiting dismantlement. We are able to make our estimates by monitoring all known nuclear weapon developments, by studying long-term trends, and by tracking the implementation of arms control treaties. http://www.thebulletin.org/article_nn.php?art_ofn=ja06norris