The U.S. military and national security community lost interest in insurgency after the end of the Cold War. Other defense issues such as multinational peacekeeping and transformation seemed more pressing and thus attracted the most attention. But with the onset of the Global War on Terror in 2001 and the ensuing involvement of the U.S. military in counterinsurgency support in Iraq and Afghanistan, insurgency experienced renewed concern in both the defense and intelligence communities. In this monograph, Dr. Steven Metz, who has been writing on insurgency and counterinsurgency for more than 2 decades, argues that this relearning process, while exceptionally important, emphasized the wrong thing, focusing on Cold War era nationalistic insurgencies rather than the complex conflicts which characterized the post-Cold War security environment. To be successful at counterinsurgency, he contends, the U.S. military and defense community must rethink insurgency.