Although fears of terror attacks run high, how common are these events and who are the perpetrators? Why is it so difficult for policymakers to craft effective counterterrorism measures? We speak to Gary LaFree, professor of criminology and criminal justice at the University of Maryland College Park, and director of the ‘National Consortium for the Study of Terrorism and Responses to Terrorism’ there. He is co-author of the new book “Countering Terrorism: No Simple Solutions.”