This article examines the different approaches of European and US policy makers to the use of force in a changing world. The truths and fallacies pertaining to these approaches lead the author to believe that the absence of a common view among the permanent members of the Security Council on what constitutes a threat to international peace and security in order to use force can have a debilitating effect on international security. For this reason the author argues that, rather than endlessly debating how old rules should be applied to new threats, what is needed is a determined effort on both sides of the Atlantic to forge a new framework for the use of force.