Central Intelligence Agency Director John Brennan takes questions after addressing the Council on Foreign Relations on March 11. The CIA has proposed deleting the email of almost all employees after they leave the agency. But some critics are saying a larger portion of the email should be preserved. Chip Somodevilla/Getty Images hide caption

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This photo provided by The Guardian in London shows Edward Snowden, who worked as a contract employee at the National Security Agency, in Hong Kong last year. AP hide caption

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Director of National Intelligence James Clapper (center), accompanied by FBI Director Robert Mueller (left) and CIA Director John Brennan, testifies on Capitol Hill on March 12, 2013. When questioned, Clapper said the NSA did not collect data on Americans. He later acknowledged his response was "clearly erroneous." Susan Walsh/AP hide caption

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Over the last dozen years, whistleblowers at the National Security Agency have had a rough track record, facing FBI raids and lawsuits. NSA/Reuters/Landov hide caption

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The Associated Press reports that the U.S. knew the British government would oversee the destruction of hard drives held by the Guardian newspaper that contained sensitive information. Raphael Satter/AP hide caption

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Speaker John Boehner prepares to speak to the media after the House passed the USA Freedom Act, an NSA reform bill aimed at restricting access to Americans' phone records. Jim Lo Scalzo/EPA/Landov hide caption

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Glenn Greenwald in April, arriving in the U.S. for the first time since documents were disclosed to him by former intelligence analyst Edward Snowden. Stan Honda/AFP/Getty Images hide caption

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Russian President Vladimir Putin as he answered questions on national TV Thursday in Moscow. Alexey Nikolsky/RIO Novosti/Kremlin pool/EPA/Landov hide caption

itoggle caption Alexey Nikolsky/RIO Novosti/Kremlin pool/EPA/Landov