The US-led war to oust the regime of Saddam Hussein elicited a wide range of responses among liberal states, from active diplomatic opposition in the prelude to war to actual combat support once hostilities commenced. These divergent responses, in part, reflected different perceptions of the legitimacy of force and international law. Furthermore, I contend that these perceptions are rooted in the unique regional security environment in which each state is situated, with states located in relatively insecure regional environments being more favorably disposed to view US military preponderance and use of force as a legitimate public good. Consequently, I hypothesize that the more insecure a state's regional security environment, the more likely it was to support, either diplomatically or militarily, the "major combat" phase of Operation Iraqi Freedom. To this end, I develop a measure of regional security based on concepts of power and polarity adapted from John Mearsheimer's The Tragedy of Great Power Politics. I then test this measure using a logistic regression analysis for 85 states located in 10 regions. The results indicate support for the hypothesis, but also illuminate the need for more research on the implications of power distributions within regional settings for international conflict in the post-Cold War era.