Employed by terrorists, a nuclear explosion and its incendiary and blast effects would cause physical destruction on a vast scale. The detonation of even a small nuclear weapon in a densely populated area would probably kill tens of thousands of people and seriously wound even more. The radiation released immediately in a nuclear explosion and the radioactive fallout of ash and debris that would probably follow would also cause serious damage to exposed individuals. What is the likelihood that terrorists could obtain and use nuclear weapons? What are some of the ways that terrorists might choose to attack nuclear targets in a highly developed country that made extensive use of nuclear power plants? These are some of the more important questions that any analysis of terrorism needs to address.