American fugitive Edward Snowden underwent more than five weeks in limbo while angering the United States and putting in doubt a planned summit between the two nations' presidents.
The United States wanted Russia to send Snowden home to face criminal charges, including espionage for disclosing in June secret American internet and telephone surveillance programs.
The White House signaled that President Barack Obama may boycott a September summit with President Vladimir Putin in Moscow.
Snowden, whose disclosures triggered an international furor over the reach of US spy operations as part of its counterterrorism efforts, thanked Russia for his temporary asylum and declared that "the law is winning".
Anatoly Kucherena, Snowden's Russian lawyer, said the 30-year-old had found shelter in a private home of American expatriates.
Putin's move aggravated relations with the United States that were already strained by Russian support for Syrian President Bashar al-Assad in that country's bloody civil war and a host of other issues.
"We see this as an unfortunate development and we are extremely disappointed by it," White House spokesperson Jay Carney told reporters in Washington.
"We are evaluating the utility of a summit, in light of this and other issues, but I have no announcement today on that."
Other high-level US-Russian talks were also put in doubt.
Discussions planned for next week between US secretary of state John Kerry, defense secretary Chuck Hagel and their Russian counterparts are now "up in the air," according to a US official, who spoke on condition of anonymity.
Snowden, a former National Security Agency contractor, has avoided the hordes of reporters trying to find him since he landed at Moscow's Sheremetyevo airport from Hong Kong on June 23.
He gave them the slip again as he left the transit area where he had been holed up.
State television showed Snowden, wearing a backpack and a blue button-up shirt, getting into a gray car at the airport, driven by a young man in a baseball cap.
"Over the past eight weeks we have seen the Obama administration show no respect for international or domestic law but in the end the law is winning," Snowden, whose first leaks were published two months ago, was quoted as saying by the WikiLeaks anti-secrecy group, which has assisted him.
"I thank the Russian Federation for granting me asylum in accordance with its laws and international obligations."
Grainy images on state television showed Snowden's document, which is similar to a Russian passport, and revealed that he had been granted asylum for a year from July 31.
'Most wanted man'
"He is the most wanted man on planet Earth," Kucherena told Reuters.
Kucherena said Snowden wanted to rent an apartment and find work in Russia, and had no immediate plans to leave.
Snowden, who had his US passport revoked by Washington, had bided his time in the transit area between the runway and passport control, which Russia considers neutral territory.
"He needs to work. He is not a rich man, and the money that he had, he has of course, spent on food," said Kucherena, who sits on two high-profile Russian government advisory bodies.
"Snowden is an expert, a very high-level expert, and I am receiving letters from companies and citizens who would eagerly give him a job. He will not have any problems," the lawyer said.
Snowden already has been offered a job by Russia's top social networking site.
A pledge not to publish more information that could harm the United States was the condition under which Putin said Snowden could receive safe harbor.
"Edward assured me that he is not planning to publish any documents that blacken the American government," Kucherena said.
Snowden was accompanied by Sarah Harrison, a WikiLeaks legal researcher.
"We would like to thank the Russian people and all those others who have helped to protect Mr Snowden. We have won the battle – now the war," WikiLeaks said on Twitter.
"I am so thankful to the Russian nation and President Vladimir Putin," the American's father, Lonnie Snowden, told Russian state television.
Bruce Fein, an attorney for Lonnie Snowden, spoke twice on Thursday with Kucherena.
The discussions were about Edward Snowden's safety – "he is fine" – and about arranging a visit to Russia by Snowden's father and his legal team to see his son, a source familiar with the discussions told Reuters.
Lonnie Snowden has not had direct contact with his son yet and "nobody knows where he [Edward] is," the source said.
The visit to Russia could occur in the next three weeks or so, the source said.
US lawmakers incensed
Prominent US lawmakers – Republicans and Democrats – condemned Russia's action and urged Obama to take stern retaliatory steps beyond the issue of the September summit.
It is not clear whether Obama might also consider a boycott of the G20 summit in Russia in September, immediately after the planned summit with Putin, or of the Winter Olympics, which Russia will host in the city of Sochi next February.
"Russia has stabbed us in the back, and each day that Mr Snowden is allowed to roam free is another twist of the knife," said Senator Chuck Schumer, a close Obama ally and fellow Democrat who urged Obama to recommend moving out of Russia the summit of G20 leaders planned for St Petersburg.
Republican senators John McCain and Lindsey Graham, already sharp critics of Putin, called Russia's action a disgrace and a deliberate effort to embarrass the United States.
They said the United States should retaliate by pushing for completion of all missile-defense programs in Europe and moving for another expansion of Nato to include Russian neighbour Georgia.
Kremlin foreign policy aide Yuri Ushakov played down concerns about the impact on relations with the United States.
"Our president has … expressed hope many times that this will not affect the character of our relations," he said.
Snowden hopes to avoid the same fate as Bradley Manning, the US Army soldier convicted on Tuesday on criminal charges including espionage and theft related to releasing classified data through WikiLeaks.
Nicaragua, Bolivia and Venezuela have offered Snowden refuge, but there are no direct commercial flights to Latin America from Moscow and he is concerned the United States would intercept any flight he takes.
Snowden also has received a marriage proposal via Twitter from Anna Chapman, the glamorous former agent who was deported to Russia from the United States in a Cold-War style spy swap in 2010.
Putin has said he wants to improve relations with the United States amid differences over the Syrian civil war, his treatment of political opponents and foreign-funded non-governmental organisations.
He would have risked looking weak if he had handed Snowden over to the US authorities.
More than half of Russians have a positive opinion of Snowden and 43% wanted him to be granted asylum, a poll released by independent research group Levada said this week. – Reuters