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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A cargo ship transits the Suez Canal en route from the Mediterranean Sea to the Gulf of Suez at the city of Suez, Egypt, on Feb. 2. Egypt controls the canal, which is vital to U.S. interests. Emilio Morenatti/AP hide caption

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The USS Enterprise passes behind a mosque as it makes its way through the Suez Canal in the city of Suez, Egypt, on Aug. 1, 2007. Ben Curtis/AP hide caption

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