A former CIA employee working as a contractor for the National Security Agency has come forward as the source behind one of the biggest leaks in U.S. history. Edward Snowden, a former CIA technical assistant now working with the NSA through the military firm Booz Allen Hamilton, revealed his identity in an interview with The Guardian of London. Snowden said he exposed top secret NSA surveillance programs to alert Americans of expansive government spying on innocents.

Edward Snowden: “The public needs to decide whether these programs and policies are right or wrong. And I’m willing to go on the record to defend the authenticity of them and say I didn’t change these, I didn’t modify the story, this is the truth, this is what’s happening, you should decide whether we need to be doing this.”

Snowden was speaking from Hong Kong, where he’s been since last month after leaving his home in Hawaii. He says he carefully vetted each document that he released to ensure it was “legitimately in the public interest.” Over the last several days, Snowden’s disclosures to The Guardian and The Washington Post have revealed a number of previously unknown surveillance operations carried out by the NSA. These include the collection of millions of U.S. call logs and a secret program called PRISM that gathers data on foreign Internet users from the servers of nine major firms, including Google, Microsoft, Apple, Yahoo! and Facebook. Other disclosures include a presidential directive laying out the guidelines for launching cyber-attacks, and a data-mining tool called Boundless Informant that details U.S. surveillance on computer and telephone networks abroad.