The post-Cold War era presented to the nations of the world the opportunity to experience peace in a way that had not been enjoyed for decades, if not centuries. However, since the end of the Cold War there have been a significant number of smaller conflicts, genocides, ethnic cleansings, and regional battles. The September 11, 2001, attacks against targets in the United States brought the strife to the US in an unexpected way. Since that day, there has been a significant level of US military activity in the world, and plenty of debate over how to do it. One of the most interesting aspects of the debate is over the "preemptive war" that was started in Iraq. While this thesis is not specifically about Operation Iraqi Freedom, it is a catalyst, of sorts, for studying the subject of the Just War Tradition and its influence on preemptive military activities.