Bruce Hoffman is a professor at Georgetown University's Walsh School of Foreign Service and the director of its Center for Security Studies and its Security Studies Program, as well as a senior fellow at the U.S. Military Academy's Combating Terrorism Center. He is also the author of Inside Terrorism (Columbia, 1998), now in its third edition.

Fernando Reinares is a professor of political science and security studies at Universidad Rey Juan Carlos and a director of the Program on Global Terrorism at Elcano Royal Institute in Madrid, Spain. He is also an adjunct professor at Georgetown University and the author of Al-Qaeda's Revenge: The 2004 Madrid Train Bombings (Columbia, 2016).