"The Four Faces of Nuclear Terrorism", a new book from the Center for Nonproliferation Studies, assesses the motivations and capabilities of terrorist organizations to acquire and use nuclear weapons, to fabricate and detonate crude nuclear explosives, to strike nuclear power plants and other nuclear facilities, and to build and employ radiological weapons or dirty bombs. The authors maintain that there is a greater likelihood today than any time in the past three decades that nuclear weapons will actually be used. This stark assessment is based upon two premises: 1) Non-state actors have emerged who seek nuclear weapons in order to use them and 2) Crude but real nuclear weapons, as distinct from radiological dispersal devices, are well within the technical reach of some terrorist organizations. The authors urge the United States and its international partners to take immediate steps to prevent the most catastrophic forms of nuclear terrorism and to reduce the consequences of the most likely nuclear terror attacks. Priority tasks include securing and reducing tactical nuclear weapons in Russia; securing, consolidating, and eliminating highly enriched uranium globally; and providing for secure storage and disposal of radioactive materials used in medicine, scientific research, and industry. The book also stresses the need to educate the public on the real risks of radiation exposure and radioactive contamination to help psychologically immunize citizens against fear of radiological attacks, which the authors conclude are all but inevitable in the coming years.