Since the end of the Cold War there has been an age of primacy marked by a series of conflicts for which powerful states have chosen to go to war over nonvital interests against much weaker state or nonstate actors. In these asymmetric conflicts, the powerful have coerced concessions, imposed regime change, and suppressed the spread of violence through counterterrorism or counterinsurgency operations. Powerful nations have largely succeeded in achieving both their military and political objectives by taking advantage of asymmetries in technology to wage war from afar, at low risk to their own forces. War outcomes have not, however, always translated into broader foreign policy objectives of long-term peace and stability. This introductory chapter provides an overview of the evolution of air power theory, presents characteristics of contemporary air warfare and measures of military and political effectiveness, and then briefly assesses the ten air wars examined in subsequent chapters.