THE COLD WAR HAS ENDED, BUT its instruments are still with us. During almost 50 years of military competition with the United States, the Soviet Union built up a stockpile of weapons that comprised more than 40,000 nuclear warheads. Behind the enormous arsenal lay a gigantic supporting infrastructure of research laboratories, test sites, and factories for producing the warheads and their delivery systems – some of which, such as submarines and other naval vessels, were themselves nuclear-powered. Although the Strategic Arms Reduction Treaty (START I), signed in July 1991, provided for significant reductions in both American and Soviet strategic nuclear forces, the agreement had not been ratified – much less implemented – when the Soviet Union ceased to exist that December, leaving nuclear weapons scattered over a new political landscape.