He later went to work for the CIA as an information technology employee and by 2007 was stationed in Geneva, Switzerland, where he had access to classified documents.
During that time, he considered going public with what he knew about the nation's secretive programs. He decided against it, he told the newspaper, because he did not want to put anyone in danger and hoped Obama's election would curtail some of the clandestine programs.
He said he was disappointed that Obama did not rein in the surveillance programs.
"Much of what I saw in Geneva really disillusioned me about how my government functions and what its impact is in the world," he said. "I realized that I was part of something that was doing far more harm than good."
Snowden left the CIA in 2009 to join a private contractor. He spent the last four years at the National Security Agency, the intelligence arm that monitors electronic communications, as a contractor with consulting giant Booz Allen Hamilton and, before that, Dell.
The Guardian reported that Snowden was working in an NSA office in Hawaii when he copied the last of the documents he planned to disclose and told supervisors that he needed to be away for a few weeks to receive treatment for epilepsy.
He left for Hong Kong on May 20 and has remained there since, according to the newspaper. Snowden is quoted as saying he chose that city because "they have a spirited commitment to free speech and the right of political dissent," and because he believed it was among the spots on the globe that could and would resist the dictates of the U.S. government.
"I feel satisfied that this was all worth it. I have no regrets," Snowden told the newspaper.
The newspaper said Snowden has been monitoring news coverage of the leaks and asked to be identified after several days of interviews.
"I have no intention of hiding who I am because I know I have done nothing wrong," Snowden is quoted as saying.
Officials said the revelations were dangerous and irresponsible. Rep. Mike Rogers, the Republican chairman of the House Intelligence Committee, said the journalists who disclosed the operations did not grasp the consequences.
"He doesn't have a clue how this thing works," Rogers told ABC's "This Week" on Sunday. "Neither did the person who released just enough information to literally be dangerous."