This book provides information on the background and current status of the regimes intended to limit the spread of nuclear, chemical, and biological weapons and missiles. Weapons of mass destruction (WMD), especially in the hands of radical states and terrorists, represent a major threat to US national security interests. Multilateral regimes were established to restrict world trade in these goods and technologies and to monitor certain civil applications. The nuclear non-proliferation regime encompasses several treaties, extensive multilateral and bilateral diplomatic agreements, multilateral organisations and domestic agencies, and the domestic laws of participating countries. The nuclear regime represents a near-universal international consensus opposing any further spread of nuclear weapons. Since the beginning of the nuclear age, US leadership has played a decisive role in the development of the regime. The regime is being challenged from several directions, as demonstrated by the Indian and Pakistani nuclear detonations in 1998. Many observers believe the success of the nuclear non-proliferation regime should be a top priority and that its outcome will strongly influence the effectiveness of other regimes dedicated to controlling chemical and biological weapons and missiles.