Defense Secretary Chuck Hagel briefs reporters at the Pentagon on Monday. Hagel and President Obama will need to fight through a wall of resistance to their proposed defense budget cuts, say former members of a defense base closing commission. Carolyn Kaster/AP hide caption

itoggle caption Carolyn Kaster/AP

Secretary of Defense Chuck Hagel attends the International Institute for Strategic Studies Regional Security Summit in the Bahraini capital Manama on Saturday. Mohammed Al-Shaikh /AFP/Getty Images hide caption

itoggle caption Mohammed Al-Shaikh /AFP/Getty Images

Concerns over China's air defense claims led Secretary of Defense Chuck Hagel to call Japan's defense minister Wednesday. Here, a man makes a call near a replica of a Chinese fighter jet displayed in Beijing Wednesday. Ng Han Guan/AP hide caption

itoggle caption Ng Han Guan/AP

Defense Secretary Chuck Hagel. Chip Somodevilla/Getty Images hide caption

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Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey, Secretary of State John Kerry, and Defense Secretary Chuck Hagel testify before the Senate Foreign Relations Committee on Tuesday. Mark Wilson/Getty Images hide caption

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U.S. Defense Secretary Chuck Hagel, center, chains his hands with his counterparts from Vietnam, right, and Thailand before the ASEAN meeting in Bandar Seri Begawan, Brunei, on Thursday. The trip's message: The U.S. is committed to its "rebalance" toward the Asia-Pacific region. Vincent Thian/AP hide caption

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Secretary of Defense Chuck Hagel with U.S. troops in Kabul, Afghanistan, on March 11. Jason Reed/pool/Getty Images hide caption

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The Pentagon. New Defense Secretary Chuck Hagel wants a review of how sexual assault cases are adjudicated by the military. Jason Reed /Reuters /Landov hide caption

itoggle caption Jason Reed /Reuters /Landov

Afghan President Hamid Karzai said in a nationally televised speech on Sunday that the U.S. and the Taliban are holding talks. Ahmad Jamshid/AP hide caption

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Afghanistan National Army soldiers and security personnel walk at the site of a suicide attack next to the Ministry of Defense main gate in Kabul on Saturday. Massoud Hossaini/AFP/Getty Images hide caption

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New Defense Secretary Chuck Hagel, left, as he was sworn in Wednesday morning at the Pentagon. His wife, Lilibet, held the Bible. Michael L. Rhodes, the Pentagon's director of administration and management, administered the oath. MC1 Chad J. McNeeley/Office of the Secretary of Defense hide caption

itoggle caption MC1 Chad J. McNeeley/Office of the Secretary of Defense