Kimberly and Frederick W. Kagan's recent commentary in The Washington Post, arguing for a force of 30,000 or more Americans in Afghanistan after 2014, is fundamentally wrong. Although their goals are sound — preventing terrorist attacks from the region on the United States — the writers' logic and conclusions about the resources required are flawed. It is possible to protect U.S. interests across that region after 2014 with a force in Afghanistan of 10,000 or fewer American troops.