Afghan National Army troops take a break while on a joint patrol and clearing operation with Butcher Troop, part of the U.S. Army's 1st Infantry Division, in eastern Afghanistan. David Gilkey/NPR/Redux hide caption

itoggle caption David Gilkey/NPR/Redux

Isutalah of the Interim Security for Critical Infrastructure force on foot patrol in northern Marjah with Marines of Golf Company, 2nd Battalion, 8th Regiment. David Gilkey/NPR hide caption

itoggle caption David Gilkey/NPR

Sgt. Joseph Garrison with Fox Company, 2nd Battalion, 8th Marine Regiment, runs through the desert near Camp Leatherneck during a drill in June 2009. Garrison was killed while on his fourth combat deployment to Afghanistan in June 2011, when he was struck by a homemade bomb in Marjah. David Gilkey/NPR hide caption

itoggle caption David Gilkey/NPR

Blackwater security contractors are seen in a helicopter in Baghdad in 2007. The company changed its name to Xe in 2009, amid controversy surrounding the killing of 17 Iraqi civilians in 2007. Khalid Mohammed/AP hide caption

itoggle caption Khalid Mohammed/AP

A Pakistani shepherd in Abbottabad walks past the hideout of al-Qaida leader Osama bin Laden, who was killed in a U.S.-led ground operation early Monday. Aamir Qureshi/AFP/Getty Images hide caption

itoggle caption Aamir Qureshi/AFP/Getty Images