The two secret programs have alarmed the world.
A U.S. man, who admitted leaking to reporters, top secret information about his country’s extensive phone and internet surveillance program, remains under the possibility of an extradition from Hong Kong where he fled to avoid arrest.
Edward Snowden, 29, revealed his identity on Sunday to The Guardian and The Washington Post as the official who spoke about the classified programs, risking decades in jail if the U.S. can extradite him from Hong Kong.
The two papers broke the stories last week and have published a series of top-secret documents outlining two surveillance programs that have received widespread condemnations.
The phone program gathers millions of U.S. phone records while searching for possible links to known terrorist targets abroad, while the internet spy program allows U.S. authorities tap into nine U.S. Internet companies to gather data that may yield clues about potential threats.
The second program, covering companies such as Facebook, Microsoft, Google, Skype, Youtube and others, affects billions of people around the world and is said to be particularly targeted at non-U.S. citizens abroad.
President Barack Obama has defended the programs as having been authorized by Congress and subject to strict supervision of a court. He also claimed phone communications of Americans were not tapped.
The NSA has asked the Justice Department to conduct a criminal investigation into the leaks.
Mr. Snowden said he acted to “protect basic liberties for people around the world” and that he had the “obligation to help free people from oppression”.
“The NSA has built an infrastructure that allows it to intercept almost everything. With this capability, the vast majority of human communications are automatically ingested without targeting,” he told the Guardian. “I don’t want to live in a society that does these sort of things… I do not want to live in a world where everything I do and say is recorded. That is not something I am willing to support or live under.”
Mr. Snowden said he did not believe he had committed a crime but said he accepted he could end up in jail and fears for people who know him.
“We have seen enough criminality on the part of government. It is hypocritical to make this allegation against me.”
Mr. Snowden said he had gone to Hong Kong because of its “strong tradition of free speech”.
“Mainland China does have significant restrictions on free speech but the people of Hong Kong have a long tradition of protesting in the streets, making their views known,” Mr. Snowden said.
Hong Kong signed an extradition treaty with the US shortly before the territory returned to Chinese sovereignty in 1997.
It was returned to Chinese rule amid constitutional guarantees for a high degree of autonomy. China, however, has responsibility over defense and foreign affairs and has exerted considerable behind-the-scenes influence over the territory’s political, financial, legal and academic spheres.
A standard visa on arrival in Hong Kong for a U.S. citizen lasts for 90 days and Mr. Snowden expressed an interest in seeking asylum in Iceland.
However, China can block any extradition if it believes it affects national defence or foreign policy issues. Under Hong Kong’s Fugitives Offenders Ordinance, Beijing can issue an “instruction” to the city’s leader to take or not take action on extraditions where the interests of China “in matters of defense or foreign affairs would be significantly affected.”