"Today, it would be easy for adversaries to introduce and detonate a nuclear explosive clandestinely in the United States. In or near a city, such an explosion would kill a great many people. Any nuclear explosion by an adversary against the United States would have repercussions that could profoundly impact the nation politically, economically, and even culturally in a variety of ways. Events would be set in motion that could affect world history, perhaps in catastrophic ways." It is a central thesis of this report that a clandestine nuclear attack and the defense against it should be treated as an emerging aspect of strategic warfare. U.S. DEFENSE PLAN AGAINST NUCLEAR ATTACKS provides information relating to: - DoD's main operational roles and missions: Discussion and recommendations - Clandestine attack scenarios vs. protection architectures - "Imperfect defenses" and improvements to intelligence capabilities - Operational changes and increased radiation detection performance - Plans for achieving the needed capabilities and effective implementation Includes a handbook intended to supply information for use in making a preliminary assessment of a situation in which possible chemical, biological or radiological materials is suspected along with a comprehensive glossary of terms and list of additional reference materials. THE DEFENSE SCIENCE BOARD TASK FORCE was established in March 2002 as part of the ongoing Defense Science Board's examination the Department of Defense's capabilities to deal with the issues of strategic terrorism and WMD proliferation. The Chemical/Biological/Radiological Incident Handbook was produced by the Chemical, Biological and Radiological (CBRN) Subcommittee of the Interagency Intelligence Committee on Terrorism (IICT).