Security Studies traces its origins to work on the causes of war. It remains the most significant subdiscipline of International Relations and, at the beginning of the twenty-first century, its concerns with the security of the international system and the individual, as well as the state, remain as pertinent and urgent as ever. While--especially since the events of 11 September 2001 and the remilitarization of US foreign policy--the focus on states and military power remains central to Security Studies, the subject also embraces economic, societal, and environmental security. Furthermore,...