By Barton Gellman

This June 9, 2013 file photo provided by The Guardian Newspaper in London shows National Security Agency leaker Edward Snowden, in Hong Kong. Snowden says his “mission’s already accomplished” after leaking NSA secrets that have caused a reassessment of U.S. surveillance policies. Snowden told The Washington Post in a story published online Monday night, Dec. 23, 2013, he has “already won” because journalists have been able to tell the story of the government’s collection of bulk Internet and phone records. (Glenn Greenwald and Laura Poitras, The Guardian, via Associated Press)

MOSCOW — Edward Joseph Snowden emerged at the appointed hour, alone, blending into a light crowd of locals and tourists.

Late this spring, Snowden supplied three journalists, including this one, with caches of top-secret documents from the National Security Agency, where he worked as a contractor. Dozens of revelations followed, then hundreds, as news organizations around the world picked up the story. Congress pressed for explanations. New evidence revived old lawsuits, and the Obama administration was obliged to declassify thousands of pages it had fought for years to conceal.

Six months after the first revelations appeared, Snowden agreed to reflect at length.

“For me, in terms of personal satisfaction, the mission’s already accomplished,” he said. “I already won. 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.”

“All I wanted was for the public to be able to have a say in how they are governed,” he said. “That is a milestone we left a long time ago.”

Snowden had come to believe a dangerous machine of mass surveillance was growing unchecked.

The NSA’s business is “information dominance,” the use of other people’s secrets to shape events. At 29, Snowden upended the agency on its own turf.

“You recognize that you’re going in blind, that there’s no model,” Snowden said, acknowledging that he had no way to know whether the public would share his views.

Snowden succeeded. Accustomed to watching without being watched, the NSA faces scrutiny it has not endured since the 1970s, or perhaps ever.

The cascading effects have made themselves felt in Congress, the courts, popular culture, Silicon Valley and world capitals. The basic structure of the Internet itself is now in question, as Brazil and members of the European Union consider measures to keep their data away from U.S. territory, and U.S. technology giants including Google, Microsoft and Yahoo take extraordinary steps to block the collection of data by their government.

People who accuse him of disloyalty, he said, mistake his purpose.

“I am not trying to bring down the NSA; I am working to improve the NSA,” he said.

He is an “ascetic,” he said. He lives off ramen noodles and chips. He has visitors. The Internet is an endless library and a window on the progress of his cause.

But Snowden knows his presence in Russia, which granted him temporary asylum Aug. 1, is easy ammunition for critics.

“There is no evidence at all for the claim that I have loyalties to Russia or China or any country other than the United States,” he said.

“If I defected at all,” Snowden said, “I defected from the government to the public.”