Written for students and general readers, this accessible book examines the evolving threat of terrorism and draws on the latest research to assess future trends. The author assumes that terrorism will remain a potent threat to the international system throughout the twenty-first century, primarily because of the convergence of two negative trends: the availability of Chemical, Biological, Radiological, and Nuclear Weapons (CBRN)--also known as Weapons of Mass Destruction--and the proliferation of terrorist organizations seeking to achieve mass casualties.