Books and Monographs
2016. From Cradle to Grave: The Lifecycle of Foreign Fighters in Iraq and Syria. West Point, NY: Combating Terrorism Center (with Daniel Milton)
2015. Explaining the Causes and Impact of Political Assassinations. West Point, NY: Combating Terrorism Center.
2013. Challengers from the Sidelines, Understanding the American Violent Far Right. West Point, NY: Combating Terrorism Center.
2009. Jewish Terrorism in Israel. New York: Columbia University Press (with Ami Pedahzur).
2008. Political Parties and Terrorist Groups. London and New York: Routledge (Second Edition, with Leonard Weinberg and Ami Pedahzur).
2005. Eastern Terrorism. Philadelphia: Chelsea House Publications.
2005. Countering Terrorism in Urban Environment - The Case of Jerusalem. Jerusalem: Jerusalem Institute (with Gadi Pahran and Ami Pedahzur).