Marc Sageman, M.D., Ph.D., is a political sociologist, forensic psychiatrist and a former foreign service officer who was based in Islamabad from 1987 to 1989, where he worked closely with Afghanistan’s mujahedin. He has advised various branches of the U.S. government in the war on terror and is a forensic psychiatrist in private practice in Washington, D.C. Among his books are Understanding Terror Networks (2004), Leaderless Jihad: Terror Networks in the Twenty-First Century (2008), Misunderstanding Terrorism (2016), and The London Bombings (2019).