"For me, in terms of personal satisfaction, the mission's already accomplished," he told the Washington Post. The newspaper said it spoke to Snowden over two days of nearly unbroken conversation in Moscow, "fueled by burgers, pasta, ice cream and Russian pastry."
It was the first extensive face-to-face interview Snowden has granted since arriving in Russia in June and being given temporary asylum there.
"I already won," Snowden said. "As soon as the journalists were able to work, everything that I had been trying to do was validated. Because, remember, I didn't want to change society. I wanted to give society a chance to determine if it should change itself."
Last week, a White House-appointed panel proposed curbs on some key NSA surveillance operations, recommending limits on a programme to collect records of billions of telephone calls, and new tests before Washington spies on foreign leaders. The panel's proposals were made in the wake of Snowden's revelations.
President Barack Obama later tried to strike a middle ground, saying some checks were needed on the NSA's surveillance, but "we can't unilaterally disarm."
In the interview, Snowden denied he was trying to bring down the NSA. "I am working to improve the NSA," he said. "I am still working for the NSA right now. They are the only ones who don't realize it."
Snowden left his post in Hawaii in May and went public with his first revelations about the NSA from Hong Kong a few weeks later. Later in June, he left for Russia and stayed at Moscow's Sheremetyevo airport until the Kremlin granted him temporary one-year asylum after nearly six weeks.
Called a champion of human rights by his admirers and a traitor by critics, Snowden lives at an undisclosed location in the Russian capital. The Washington Post said he was unaccompanied when he met the reporter for the interview, and did not try to communicate furtively. He said he has had access to the Internet and to lawyers and journalists throughout his stay in Russia.
Snowden called himself "an indoor cat", and says he rarely leaves his house. "I just don't have a lot of needs," he said. "Occasionally there's things to go do, things to go see, people to meet, tasks to accomplish.
"But it's really got to be goal-oriented, you know. Otherwise, as long as I can sit down and think and write and talk to somebody, that's more meaningful to me than going out and looking at landmarks."
Snowden said he was an ascetic and lived off ramen noodles and chips. He has visitors and many of them bring books, but they pile up, unread.
He denied he had loyalties to Russia or China.
"I have no relationship with the Russian government," he said. "I have not entered into any agreements with them. If I defected at all, I defected from the government to the public."