Staff members at the Army Experience Center in Philadelphia demonstrate the Humvee interactive simulator in 2009. Matt Rourke/AP hide caption

itoggle caption Matt Rourke/AP

Tucson Police officer Angel Ramirez and a man suspected of trespassing, in May. While many law enforcement officials support the new Arizona immigration law, others worry it will hurt relations with the community. Scott Olson/Getty Images hide caption

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U.S. Navy and South Korean ships sail in a 13-ship formation led by the Los Angeles-class attack submarine USS Tucson on Monday in the East Sea off the Korean peninsula. North Korea has promised "sacred war" in response to the naval exercises, which began on Sunday. U.S Navy via Getty Images hide caption

itoggle caption U.S Navy via Getty Images

A U.S. Marine from Bravo Company of the 1st Battalion, 2nd Marines runs for cover during a gun battle as part of an operation to clear the area of insurgents near Musa Qaleh, in northern Helmand province, southern Afghanistan, July 23. Kevin Frayer/AP Photo hide caption

itoggle caption Kevin Frayer/AP Photo