U.S. Army Gen. Martin E. Dempsey, left, chairman of the Joint Chiefs of Staff, arrives on Forward Operating Base Sharana in Paktika province, Afghanistan, April 7, 2013. DOD photo by D. Myles Cullen

U.S. Defense Secretary Chuck Hagel places a wreath as Israeli Defense Minister Moshe Yaalon and Robert Ozzett, Yad Vashem’s director of libraries, watch at the Yad Vashem Holocaust Memorial in Jerusalem, April 21, 2013. DOD photo by Erin A. Kirk-Cuomo

U.S. Defense Secretary Chuck Hagel returns a salute from a Saudi Army officer during a meeting with Saudi Arabia’s Crown Prince Salman bin Abdulaziz al Saud, the country's defense minister, in Riyadh, Saudi Arabia, April 23, 2013. DOD photo by Erin A. Kirk-Cuomo

U.S. Marine Corps Lance Cpl. Ryan Burdge, front, uses a metal detector during counter improvised explosive device training on Camp Leatherneck in Helmand province, Afghanistan, April 3, 2013. Burdge, a rifleman, is assigned to Kilo Company, 3rd Battalion, 4th Marine Regiment. U.S. Marine Corps photo by Sgt. Tammy K. Hineline

U.S. Army Pfc. Robert Tucker talks on his radio while providing rooftop security for the customs checkpoint at Torkham Gate in Afghanistan's Nangarhar province, April 24, 2013. Tucker, an infantryman, is assigned to the 101st Airborne Division's Company A, 1st Battalion, 327th Infantry Regiment, 1st Brigade Combat Team. U.S. Army photo by Spc. Margaret Taylor

U.S. soldiers patrol near traffic from Pakistan at the Torkham Gate customs checkpoint in Afghanistan's Nangarhar province, April 24, 2013. U.S. Army photo by Spc. Margaret Taylor

A CH-47F Chinook helicopter transports equipment and supplies to the 7,200-foot level of Kahiltna Glacier, April 26, 2013. Crews, assigned to the 1st Battalion, 52nd Aviation Regiment, aided the National Park Service by transporting equipment and supplies to the 7,200-foot level of the glacier to set up a base camp for climbers attempting Mount McKinley this summer. U.S. Army photo by John Pennell

A U.S. sailor aboard the Military Sealift Command dry cargo and ammunition ship USNS Richard E. Byrd attaches cargo to an MH-60S Seahawk helicopter while conducting a replenishment with the aircraft carrier USS Nimitz underway in the Pacific Ocean, April 28, 2013. The Seahawk is assigned to Helicopter Sea Combat Squadron 6. U.S. Navy photo by Seaman Apprentice Aiyana Paschal