If history is any guide, Clausewitz’s theory of the center of gravity will remain a contested concept. Decades of research and debate have clarified some of its finer points, but consensus on the basic nature of the theory is still missing. Nonetheless, military practitioners continue to embrace the concept with enthusiasm; some have even attempted to apply it recently in the campaigns in Iraq and Afghanistan. The U.S. military currently defines a center of gravity as a “source of power that provides moral or physical strength, freedom of action, or will to act.” This definition has some shortcomings, such as its insistence on using the word “source”, which unnecessarily complicates matters. However, it has succeeded in clarifying the distinction between centers of gravity and other operational concepts, such as “decisive points” or “critical vulnerabilities”. That is clearly a step forward from the situation that existed in the 1980s and 1990s, when the term was being used to describe “anything worthy of being attacked.”