Lt. Gen. William Caldwell (Feb. 27, 2011 file photo). U.S. Navy Petty Officer 2nd Class Ernesto Hernandez Fonte /AP hide caption

itoggle caption U.S. Navy Petty Officer 2nd Class Ernesto Hernandez Fonte /AP

A girl stands in the middle of a poppy field as Marines pass by on patrol. David Gilkey/NPR hide caption

itoggle caption David Gilkey/NPR

Corporal Daniel Wheeler, Bravo Co. 1/5 Marines, walks through a waist high wheat field on a patrol in Sangin District near the Helmand River in southern Afghanistan earlier this month. David Gilkey /NPR hide caption

itoggle caption David Gilkey /NPR

Secretary of State Hillary Clinton speaks following the death of Osama bin Laden, Monday, May 2, 2011. Jacquelyn Martin/ASSOCIATED PRESS hide caption

itoggle caption Jacquelyn Martin/ASSOCIATED PRESS