From the times of the Roman legion to the thunderous roar of the Soviet T-34 tanks, wars have shaped and literally drawn the boundaries of humanity. Although wars in contemporary times are less frequent than a few centuries ago, modern wars are more lethal and destructive. It is this singular feature -large scale destruction- that sets wars apart from other forms of conflict. Wars have been waged in various intensities and degrees and by diverse actors, but have traditionally been seen as the domain of states. In medieval times, wars were the "sports" of kings. Conceptually, war is defined as an armed conflict involving at least two nation-states. How does this characterization of war explain the types of conflicts that imperil a state's ...