Since 1980, the number of countries possessing the capacity to manufacture and deliver nuclear weapons has grown dramatically, increasing the chances of accidental nuclear exchanges. In addition to the traditional nuclear powers of the United States, Russia, China, the United Kingdom, and France, some newly independent former Soviet republics (Ukraine, Kazakhstan, Uzbekistan, and Georgia) may retain some of the weapons systems from the old Soviet Union. Also, four other countries are now judged by many authorities to possess nuclear weapons capability: Israel, India, Pakistan, and South Africa. While the stockpile of weapons of these countries is small (ranging from a minimum of 510 weapons in Pakistan to a maximum of 50– 200 weapons in Israel), the proliferation of countries capable of using nuclear warheads in wartime threatens global security.

In addition to countries that already possess the capacity to make and deliver nuclear weapons, seven other countries— Argentina, Brazil, Iran, Iraq, Libya, North Korea, and Taiwan— have or recently have had active nuclear weapons programs and may possess nuclear weapons capacity. Finally, there are countries— virtually all of them in the developed economies of the world— that possess the technological capacity to manufacture nuclear weapons and delivery systems but have chosen not to develop nuclear weapons programs. These countries include, among others, Canada, most western and eastern European countries (other than Britain or France), South Korea, Japan, Australia, and New Zealand.