Defense Secretary Leon E. Panetta watches flight deck operations onboard USS Enterprise with Navy Rear Adm. Walter E. Carter Jr., commander of the Enterprise Strike Group, in the Atlantic Ocean, Jan. 21, 2012. The Enterprise Carrier Strike Group conducted a composite training unit exercise.DOD photo by U.S. Navy Petty Officer 1st Class Chad J. McNeeley DOD photo by U.S. Navy Petty Officer 1st Class Chad J. McNeeley

U.S. Army Spc. Robert Irwin conducts a security patrol in Afghanistan's Paktya province, Jan. 30, 2012. Irwin is an infantryman assigned to Dog Company, Task Force Gold Geronimo, part of Spartan Brigade. U.S. Army photo by Staff Sgt. Jason Epperson

Air Force Capt. Brandon Lavalley breaks right on a final approach over northern Las Vegas during day three of Red Flag 12-2 on Nellis Air Force Base, Nev., Jan. 25, 2012. Lavalley is a pilot assigned to the 4th Fighter Squadron. Coalition partners from South Korea and Saudi Arabia participated in the joint training exercise. U.S. Air Force photo by Master Sgt. Benjamin Bloker

Army Vice Chief of Staff Gen. Peter W. Chiarelli walks across the parade field during his retirement ceremony on Joint base Myer-Henderson Hall in Arlington, Va., Jan. 31, 2012. DOD photo by Erin A. Kirk-Cuomo

Army Vice Chief of Staff Gen. Peter W. Chiarelli salutes as the national anthem plays during his retirement ceremony on Joint Base Myer-Henderson Hall in Arlington, Va., Jan. 31, 2012. Chiarelli's wife, Beth, joined him. DOD photo by Erin A. Kirk-Cuomo

Deputy Defense Secretary Ashton B. Carter shakes hands with Erian Idrissov, Kazakhstan's ambassador to the United States, as he welcomes Kazakhstan's Foreign Affairs Minister Yerzhan Kh. Kazykhanov, far left, to the Pentagon, Jan. 31, 2012. DOD photo by Glenn Fawcett

U.S. Army Cpl. William Hopkins looks through the scope of a Barrett .50-Cal. while Army Sgt. Lucas Cordes waits for the UH-60 Black Hawk helicopter to turn around so they can begin an aerial firing exercise over Logar province, Afghanistan, Jan. 26, 2012. Hopkins is a spotter and Cordes is a sniper team leader assigned to the 82nd Infantry Division's Company F, 2nd Aviation Assault Battalion, 82nd Combat Aviation Brigade. U.S. Army photo

Defense Secretary Leon E. Panetta speaks at the retirement ceremony for Army Vice Chief of Staff Gen. Peter W. Chiarelli on Joint Base Myer-Henderson Hall in Arlington Va., Jan. 31, 2012. DOD photo by Erin A. Kirk-Cuomo