This comprehensive yet concise introduction to international security explores the constantly changing conditions that lead to an insecure world. During the Cold War, the Soviet-American nuclear rivalry generated insecurity. Since then, state-based nuclear threats have diminished while the threat of non-state actors wielding weapons of mass destruction has increased. A global surge in mass-casualty terrorism, persistent and costly intrastate wars, and environmental threats have reshaped our thinking about security threats and how best to respond to them. Now in a thoroughly updated edition, the text considers today's security agenda, including the threat posed by the spread of infectious disease, drug trafficking and competition for petroleum, ethnic rebellions, transnational criminal and terrorist organizations, and wars in cyberspace and on the ground against elusive individuals and shadowy organizations rather than states. The authors show, in other words, how the quest for security has become far more salient than it was during the euphoric days of the post-Cold War period and far more complicated than it was during the Cold War as threats are increasingly transnational, interconnected, and stateless. Seeking Security in an Insecure World offers a broad overview of both traditional and 'new' conceptions of security. With clear and lively prose, compelling examples, and solid scholarship, it engages both students of international relations and general readers who wish to gain a better understanding of what security means today and how it can best be achieved.