The Islamic State is a byproduct of the 2003 American intervention in Iraq and the subsequent American departure in 2011. At its peak in late 2014, the group held more than 100,000 square kilometers of territory with a population of nearly 12 million, mostly in Iraq and Syria. Beginning in 2015, the Islamic State began to lose territory as it faced increasingly effective resistance. Still, the Islamic State continues to conduct and inspire attacks around the world. This report assesses the threat the Islamic State poses to the United States and examines four possible strategies to counter the group: disengagement, containment, rollback "light" (with a reliance on local forces backed by U.S. special operations forces, Central Intelligence Agency and other intelligence assets, and airpower), and rollback "heavy" (adding the employment of American conventional forces in ground combat). The authors conclude that the United States should pursue a light rollback strategy. They also recommend additional steps, such as rebalancing counterterrorism efforts to address grievances, loosening restrictions on U.S. military operations, increasing U.S. military posture in Africa, and tightening restrictions in the Islamic State's internet access.

This research was conducted within the International Security and Defense Policy Center of the RAND National Security Research Division (NSRD).

This report is part of the RAND Corporation research report series. RAND reports present research findings and objective analysis that address the challenges facing the public and private sectors. All RAND reports undergo rigorous peer review to ensure high standards for research quality and objectivity.

Permission is given to duplicate this electronic document for personal use only, as long as it is unaltered and complete. Copies may not be duplicated for commercial purposes. Unauthorized posting of RAND PDFs to a non-RAND Web site is prohibited. RAND PDFs are protected under copyright law. For information on reprint and linking permissions, please visit the RAND Permissions page.

The RAND Corporation is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.