Afghan soldiers stand at attention during a ceremony transferring authority from NATO-led troops to Afghan security forces in Afghanistan's Kunar province. The transfer of responsibility for security from NATO-led ISAF forces to Afghan troops is scheduled to be completed by the end of 2014. Rahmat Gul/AP hide caption

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U.S. Army Special Forces ride horseback as they work with members of the Northern Alliance in Afghanistan in 2001. AP hide caption

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Female Marines unload their rifles after a patrol with Afghan soldiers in Helmand province in June. The Marine Corps leadership has started an experiment to determine whether female Marine lieutenants have what it takes to become infantry officers and lead on the battlefield. Adek Berry/AFP/Getty Images hide caption

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Afghan children run to school on Sept. 24. Whoever takes over as the next U.S. president will have to determine how many troops will remain after the December 2014 deadline to help with long-term security. Jeff Pachoud/AFP/Getty Images hide caption

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Female Marines unload their rifles after a patrol with Afghan soldiers in Helmand province in June. The Marine Corps leadership has started an experiment to determine whether female Marine lieutenants have what it takes to become infantry officers and lead on the battlefield. Adek Berry/AFP/Getty Images hide caption

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Between two farm fields in Sharpsburg, Md., there was a sunken road, which Confederates used as a rifle pit until they were overrun by federal troops. The road has since been known as "Bloody Lane." Library of Congress hide caption

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Spc. Ben Purvis (center) helps train Afghan troops on how to use mortars in the eastern province of Kunar in June. The top U.S. commander in Afghanistan, Gen. John Allen, points to several factors in the rise of "insider attacks" on American forces. He says relations between U.S. and Afghan troops are good overall. Lucas Jackson/Reuters/Landov hide caption

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Gen. Norton Schwartz (shown here in October 2010) is stepping down as the top U.S. Air Force officer. Tim Sloan/AFP/Getty Images hide caption

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U.S. investigators allege that Afghan Gen. Ahmad Zia Yaftali stole tens of millions of dollars' worth of medicine from the Mohammad Daud Khan military hospital in Kabul. He has been removed from that post, but has not been prosecuted. He's shown here at the hospital on Dec. 18, 2010. Altaf Qadri/AP hide caption

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