Can the use of force first against a less-than-imminent threat be both morally acceptable and consistent with American values? In this timely book Mark Totten offers the first in-depth, historical examination of the use of preemptive and preventive force through the lens of the just war tradition. Although critical of the American incursion into Iraq as a so-called “preemptive war,” Totten argues that the new terrorist threat nonetheless demands careful consideration of when the first use of force is legitimate. The moral tradition, he concludes, provides a principled way forward that reconciles American values and the demands of security.