The May 1997 Report of the Quadrennial Defense Review (QDR) concluded that the threat or use of nuclear, biological, or chemical (NBC) weapons is a likely condition of future warfare and could occur in the early stages of war to disrupt U.S. operations and logistics. These weapons may be delivered by ballistic missiles, cruise missiles, aircraft, special operations forces, or other means. In many of the world’s regions where the United States is likely to deploy forces—including Northeast Asia and the Middle East—potential adversaries have chemical and/or biological weapons and the missile systems to deliver them, and actively seek nuclear weapons. Potential adversaries may seek to counter American conventional military superiority using less expensive and more attainable, asymmetrical means, including NBC weapons. To meet this challenge, as well as the possibility that NBC weapons might also be used in some smaller-scale contingencies, U.S. forces must be properly trained and equipped to operate effectively and decisively in the face of NBC attacks. The first section of this report details the proliferation of NBC weapons and the threat it poses to U.S. interests and forces.