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

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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

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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

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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

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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

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The aircraft carrier USS Enterprise, shown departing from Naval Station Norfolk on Jan. 13, is now in the Red Sea, with its dozens of warplanes, waiting to see if it's needed for any Libyan operation. U.S. Navy/Getty Images hide caption

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President Ronald Reagan gestures during a news conference at the White House in January 1986, when he said there was "irrefutable evidence" that Libyan leader Moammar Gadhafi was involved in airport attacks in Rome and Vienna in December 1985. Scott Stewart/AP hide caption

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An F-15C Eagle aircraft returns to base after a mission during Operation Deny Flight, the United Nations-sanctioned no-fly-zone action over Bosnia and Herzegovina in 1998. Retired Navy Capt. Tom Parker, who flew no-fly-zone missions in the Balkans, says the strategy could work in Libya. But Defense Secretary Robert Gates and others argue that it wouldn't be easy. U.S. Air Force/Getty Images hide caption

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A U.S. soldier records video footage while blowing up an improvised explosive device found by an Afghan villager in Kandahar province on Dec. 29. The military is using new technology — sensors attached to American aircraft — to sniff out roadside bombs. Behrouz Mehri/AFP/Getty Images hide caption

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Frank Buckles during a 2008 ceremony honoring him on Capitol Hill in Washington, D.C. Karen Bleier/AFP/Getty Images hide caption

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