Nuclear, biological, and chemical (NBC) weapons delivered covertly by terrorists or hostile governments pose a significant and growing threat to the United States and other countries. Although the threat of NBC attack is widely recognized as a central national security issue, most analysts have assumed that the primary danger is military use by states in war, with traditional military means of delivery. The threat of covert attack has been imprudently neglected.Covert attack is hard to deter or prevent, and NBC weapons suitable for covert attack are available to a growing range of states and groups hostile to the United States. At the same time, constraints on their use appear to be eroding. This volume analyzes the nature and limits of the covert NBC threat and proposes a measured set of policy responses, focused on improving intelligence and consequence-management capabilities to reduce U.S. vulnerability.About the authors: Richard A. Falkenrath is Assistant Professor of Public Policy at Harvard"s Kennedy School of Government. He served as Executive Director of the Belfer Center for Science and International Affairs (BCSIA) and, before that, as a Research Fellow. He is the author and co-author of Shaping Europe"s Military Order (1995), Avoiding Nuclear Anarchy (1996), America"s Achilles" Heel:Nuclear, Biological, Chemical Terrorism and Covert Attack (1998), and numerous journal articles and chapters of edited volumes. Falkenrath has been a Visiting Research Fellow at the German Society of Foreign Affairs (DGAP) in Bonn. He holds a PhD from the Department of War Studies, King"s College, London, where he was a British Marshall Scholar, and is a summa cum laude graduate of Occidental College, Los Angeles, with degrees in economics and international relations. He is on leave in 2001-2002 and is currently serving as Director for Counterproliferation and Homeland Defense at the National Security Council.Bradley A. Thayer is Assistant Professor of Political Science at the University of Minnesota, Duluth.