The U.S. military wants Afghan troops to begin taking the lead role in combat operations. Here, Afghan cadets who are joining the army are shown at their graduation ceremony on Dec. 18 in the northern city of Mazar-i-Sharif. Qais Usyan/AFP/Getty Images hide caption

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The chairman of the U.S. Joint Chiefs of Staff, Gen. Martin Dempsey (left), is in Israel to talk about the growing tension with Iran. Here, Dempsey speaks with Israel's top military officer, Lt. Gen. Benjamin Gantz, during a meeting at NATO headquarters in Brussels on Wednesday. Virginia Mayo/AP hide caption

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A member of Iran's navy participates in a drill on Dec. 28, 2011, in the Sea of Oman. Tehran is threatening to close the strategic Strait of Hormuz at the mouth of the Persian Gulf, in retaliation for new sanctions by the West. Ali Mohammadi/AP hide caption

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Defense Secretary Leon Panetta and Joint Chiefs Chairman Gen. Martin Dempsey take part in a news conference at the Pentagon in Washington in November 2011. The Obama administration is unveiling its new military strategy Thursday. Critics fear it could hamper the U.S. ability to fight two wars at once. Evan Vucci/AP hide caption

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Marine Staff Sgt. Frank Wuterich talks to the media as his attorney, Neal Puckett, looks on after a 2010 pretrial hearing at Camp Pendleton in California. Wuterich is charged with voluntary manslaughter in the deaths of 24 Iraqi civilians in 2005. Chris Carlson/AP hide caption

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As many as 5,000 private security contractors will be protecting U.S. diplomats in Iraq. The U.S. Embassy compound (above) and several consulates will have about 15,000 workers, making it the largest diplomatic operation abroad. Lucas Jackson/Reuters/Landov hide caption

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Gen. David Petraeus (center, with no gun) walks with troops in 2007 in Baqouba, Iraq. The area had recently been seized back from al-Qaida control with help from U.S. forces who were part of the surge. The surge is widely credited with changing the course of the war; now, some experts are debating how much credit it deserves. Chris Hondros/Getty Images hide caption

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A day after leaving Iraq last week, U.S. Army soldiers from the 1st Cavalry Division lined up their armored vehicles near Kuwait City, Kuwait. Armored equipment will not stay behind after troops leave Iraq, but other property may. Joe Raedle/Getty Images hide caption

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