Edward Snowden, who provided secret U.S. intelligence documents to several media outlets, may have duped as many as 25 NSA colleagues into giving him their login information, according to Reuters. He's seen here in an image from an October TV report. AFP/Getty Images hide caption

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The seal of the CIA at the agency's headquarters in Virginia. Greg E. Mathieson Sr. /MAI/Landov hide caption

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An image of Edward Snowden on the back of a banner is seen infront of the U.S. Capitol during a protest against government surveillance on October 26, 2013 in Washington, D.C. Mandel Ngan /AFP/Getty Images hide caption

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German Chancellor Angela Merkel and President Obama in September at the G20 summit in Russia. She and other leaders have objected after hearing that the NSA was listening to their phone calls. Anton Denisov/Host photo agency/Getty Images hide caption

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News of U.S. surveillance in Europe has met with distrust and anger; officials are heading to Washington to discuss matters next week. Here, members of an artists' group paint a mural called "Surveillance of the Fittest" on a wall in Cologne, Germany, on Thursday. Frank Augstein/AP hide caption

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Massive government surveillance of Americans' phone and Internet activity is drawing protests from civil liberties groups, but major legal obstacles stand in the way of any full-blown court hearing on the practice. Among them: government claims that national security secrets will be revealed if the cases are allowed to proceed. Patrick Semansky/AP hide caption

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U.S. Ambassador to France Charles Rivkin (in red tie) leaves the Foreign Ministry in Paris after being summoned Monday following reports that the National Security Agency spied on French citizens. Thibault Camus/AP hide caption

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