The September 11, 2001, terrorist attacks and the U.S. response—the global war on terrorism—have changed the world, and the terrorist enterprise that we know as al-Qaeda has changed with it. The current status of al-Qaeda’s network remains unclear, but it is certain that it and other terrorist groups continue to threaten the lives and well-being of Americans, at home and abroad, and the security of our friends and allies. This continuing danger leads to ongoing U.S. and international efforts to monitor, disrupt, and dismantle terrorist groups before they can cause large-scale destruction to our people or our interests.

The objective of this RAND Corporation study, undertaken as part of a project entitled “Beyond al-Qaeda: Countering Future Terrorist and Other Nontraditional Threats to U.S. Security,” is to understand the shape of future threats to the United States and U.S. security interests from terrorist and other extremist organizations.