1. Valuable open-source reference material for estimated deployments of nuclear weapons include: William M. Arkin and Richard Fieldhouse, Nuclear Battlefields: Global Links in the Arms Race (Harper Collins, 1985); William M. Arkin et al., Taking Stock: Worldwide Nuclear Deployments 1998 (Natural Resources Defense Council, 1998); Thomas B. Cochran et al., The U.S. Nuclear War Plan: A Time for Change (Natural Resources Defense Council, 2001); Joseph Cirincione et al., Deadly Arsenals: Nuclear, Biological, and Chemical Threats (Carnegie Endowment for International Peace, 2005); SIPRI Yearbook, various issues; and the Monterey Institute for International Studies open-source research database on the Nuclear Threat Initiative website available at http://www.nti.org/e_research/profiles/index.html .
2. For the period of 1951-1977, see Robert S. Norris, William M. Arkin, and William Burr, "Where They Were," Bulletin of the Atomic Scientists, November/December 1999, pp. 26-35, 66-67, and "How Much Did Japan Know?" Bulletin of the Atomic Scientists, January/February 2000, pp. 11-13, 78-79.
3. Defense Department, "Proliferation: Threat and Response," November 1997 (sheet 54 of web version); Taking Stock: Worldwide Nuclear Deployments 1998, pp. 33, 81-87. According to Securing the Bomb 2008 by Matthew Bunn (Project on Managing the Atom, November 2008), "The total number of warhead sites in Russia is not publicly known, but appears to be in the range of 110-130, including both permanent and temporary sites, but not counting the front-line tactical sites that may no longer have warheads day-to-day." In Charles L. Thornton's December 2003 presentation, "U.S. Efforts to Secure Russia's Nuclear Warheads: Background and Issues," before the Russian-American Nuclear Security Advisory Council, he estimated a total of 150-210 sites of which 110-150 were permanent storage sites.
4. In 2002, the Russian government announced, "All nonstrategic nuclear munitions have been transferred to the central storage facilities of the Ministry of Defense." See Ministry of Foreign Affairs of the Russian Federation, "Statement of the delegation of the Russian Federation at the First Session of the Preparatory Committee for the 2005 NPT Review Conference under Article VI of the Treaty," April 24, 2002.
5. Weapons are also occasionally present at an unknown number of temporary storage sites when in transit between bases and production facilities.