A 29-year-old government contractor revealed himself on Sunday as the source of bombshell leaks of US monitoring of Internet users and phone records, as US intelligence pressed for a criminal probe.
Edward Snowden, who has been working at the National Security Agency for the past four years, admitted his role in the leaks in a video interview posted on the website of the Guardian that clearly showed his face.
"My sole motive is to inform the public as to that which is done in their name and that which is done against them," he said.
He said he was willing to sacrifice a comfortable life "because I can't in good conscience allow the US government to destroy privacy, internet freedom and basic liberties for people around the world with this massive surveillance machine they're secretly building."
A former technical assistant for the CIA, Snowden worked for the NSA as an employee of various outside contractors, including Dell and Booz Allen Hamilton, his current employer.
He flew to Hong Kong on May 20 after copying the last set of documents he intended to disclose at the NSA's office in Hawaii, the Guardian said, adding that he has remained there ever since, holed up in a hotel room.
The British newspaper said it was revealing Snowden's identity at his own request.
"I have no intention of hiding who I am because I know I have done nothing wrong," Snowden said.
He acknowledged fears of being "rendered"—summarily detained without due process and taken into secret detention by the CIA or its partners—or taken in for questioning by Chinese authorities.
"And that is a concern I will live with for the rest of my life, however long that happens to be," he said.
The leaks published in The Guardian and the Washington Post have set off a furor, with President Barack Obama and the chief of US intelligence defending the secret programs as vital to keeping Americans safe.
Director of National Intelligence James Clapper confirmed on Saturday that the NSA uses a program called PRISM to gather data trails left by targeted foreign citizens using the Internet outside the United States.
A separate program, also disclosed by The Guardian, has been used to scoop up the telephone records of millions of Americans.
In an interview with NBC News, portions of which aired Sunday, Clapper called the disclosures "literally gut-wrenching" and said they had caused "huge, grave damage" to US intelligence capabilities.
"The NSA has filed a crimes report on this already," he told NBC.
He said he was "profoundly offended" that a disgruntled intelligence officer was a source for the leak to the Post. "This is someone who for whatever reason has chosen to violate a sacred trust for this country," he said.
"And, so, I hope we're able to track down whoever's doing this, because it is extremely damaging to, and it affects the safety and security of this country."
Glenn Greenwald, the Guardian reporter who brought to light the PRISM program and the separate program to gather US phone records, said the public had a right to know and openly debate what the government was doing.
"Every time there's a whistleblower, someone who exposes government wrongdoing, the tactic is to demonize them as a traitor," he told ABC.
"What they were seeing being done in secret, inside the United States government, is so alarming they simply want one thing.
"And that is, they want the American people to learn about this massive spying apparatus and what the capabilities are, so we can have an open, honest debate."
Clapper said he understood public concerns about the invasion of privacy and threats to civil liberties, but that "a lot of what people are seeing and reading in the media is a lot of hyperbole."
He said two plots have been foiled through information obtained through the programs, both in 2009—one a bomb attack on New York subways, and another linked to David Headley, a conspirator in the 2008 Mumbai attacks.
"I find it a little ironic that several weeks ago, after the Boston bombings, we were accused of not being sufficiently intrusive," he said.
The intelligence chief has declassified some details of the PRISM program in the face of a storm of controversy over suggestions the government had backdoor access to the servers of Internet giants like Google, Facebook and Yahoo.
Internet service providers denied they had given the government unfettered access to customer data, insisting they did so only when compelled by law.
Under PRISM, which has been running for six years, the US National Security Agency can issue directives to Internet firms demanding access to emails, online chats, pictures, files, videos and more uploaded by foreign users.
But in his statement Saturday, Clapper said the government must apply to a secret US court for permission to target individuals or entities, then issue a request to the service provider.
He admitted that data on US citizens might be "incidentally intercepted" in the course of targeting a foreign national, but said this would not normally be shared within the intelligence community unless it confirmed a threat.
Obama has defended the phone and Internet data trawls, saying America was "going to have to make some choices between balancing privacy and security to protect against terror.
But civil liberties and privacy groups have raised alarm at both programs, which some have branded "Orwellian" and possibly unconstitutional.
Explore further: Five ways to fight online abuse with good manners