Terrorism is not an entity; it is a method. Even confining ourselves to militarist Islamic groups, the divisions are frequently more significant than an outsider is likely to assume. Individuals, groups, causes, and ideologies all come and go. Following the killing of Osama bin Laden in May 2011, al Qaeda and its associated groups underwent a profound transformation, one that led to the rise of ISIS – the so-called Islamic State of Iraq and Syria. The players and the stages of the movement both diversified and became more fragmented. This month Cato Unbound is pleased to welcome renowned counterterrorism expert Ali Soufan, who has written a lead essay discussing the changing face of these violent organizations.

Joining him to discuss are the Cato Institute’s own Christopher Preble and Seth G. Jones of the Johns Hopkins University’s School of Advanced International Studies. Comments are open through the end of the month, and we welcome readers’ feedback.