Most world leaders agree that nuclear terrorism represents the gravest international security challenge today. Many scholars and practitioners, however, argue that the United States remains ill-prepared to cope with this serious and real threat. What role should the U.S. play in confronting and combating this danger? Is nuclear terrorism preventable? What steps have the U.S. already taken to prevent a nuclear catastrophe and what future steps should the U.S. government take? Esteemed scholars, scientists and policymakers address these crucial questions from all sides – strategic, tactical, ideological, and technical. Employing several vantage points, this special issue of The ANNALS clarifies and assesses the threat of a nuclear terrorist attack and examines possible solutions for preventing such a catastrophic event. The papers in this volume take a comprehensive historical look at the development of the threat of nuclear terrorism, and assesses how that threat has changed over time. The highly distinguished list of contributors to this thought-provoking issue provides readers with an authoritative overview of this critical and timely topic. Students, scholars, policymakers, and practitioners will find this collection a valuable resource for understanding the current threat level of nuclear terrorism as well as practical recommendations for reducing the risk of a nuclear terrorist attack.