A North Korean soldier (left) and a South Korean soldier stand opposite each other at the demilitarized zone separating the two Koreas. Yonhap/AFP/Getty Images hide caption

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Director of National Intelligence Dennis Blair, seen here in February, offered his resignation Thursday. During the 16 months on the job, Blair struggled to establish his authority over the CIA and other U.S. intelligence agencies. Manuel Balce Ceneta/AP hide caption

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Iranian President Mahmoud Ahmadinejad addresses the Nuclear Nonproliferation Treaty conference Monday at United Nations headquarters. Richard Drew/AP hide caption

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Iranian President Mahmoud Ahmadinejad (foreground) visits the Natanz Uranium Enrichment Facility some 200 miles south of the capital, Tehran, in this April 8, 2008, photo issued by the Iranian president's office. Iranian President's Office/AP hide caption

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President Obama talks about U.S. cybersecurity in May 2009. Obama has described U.S. computer networks as a "strategic national asset," and promised to "deter, prevent, detect and defend against" cyberattacks. Ron Edmonds/AP hide caption

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Director of National Intelligence Dennis Blair testifies before the House Intelligence Committee in February on the annual threats assessment of the U.S. intelligence community. Manuel Balce Ceneta/AP hide caption

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