The White House said it was "extremely disappointed" with Russia's decision to grant temporary asylum to US intelligence leaker Edward Snowden, casting doubt on whether high-level talks between the countries will proceed next week and jeopardising an autumn summit between their leaders.
Defying US requests for Mr Snowden to be expelled, Russia gave the former intelligence contractor asylum for a year. This allowed him to leave the transit area of Sheremetyevo airport in Moscow where he had holed up for a month, unable to travel after the US authorities revoked his passport.
Mr Snowden (29), who has revealed details of sweeping phone and internet surveillance in the US and overseas through leaks to the Guardian and Washington Post, left the Russian airport in a taxi.
He was accompanied by Sarah Harrison, a legal adviser to anti-secrecy group Wikileaks, which said the one-time US contractor had headed to a "secure, confidential" location.
Wikileaks published comments from Mr Snowden in which he thanked Russia for acting “in accordance with its laws and international obligations”.
“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,” he said.
The US had asked Russia to send Mr Snowden home to face espionage charges but was given no advance notice of Moscow's decision to grant him sanctuary for a year.
Relations between the two countries, already strained over their opposing positions on the two-year conflict in Syria, could deteriorate further over Russia's decision.
The White House has said that the move was not positive for US-Russian relations and that an autumn summit between US president Barack Obama and Russian president Vladimir Putin was being re-evaluated.
“We’re very disappointed, extremely disappointed in Russia’s decision to provide temporary asylum to Mr Snowden,” White House press secretary Jay Carney said.
"We made clear both privately and publicly that there was ample legal justification for his expulsion from Russia and return to the United States. "
Mr Carney described Mr Snowden’s possession of highly sensitive classified information “outside of secure areas” as both “a huge risk and violation”.
“Mr Snowden is not a whistleblower or a dissident,” he said. “He is accused of leaking classified information. He should be returned to the United States as soon as possible.”
Wikileaks founder Julian Assange praised the move to grant Mr Snowden asylum as a victory in the fight against Mr Obama's "war on whistleblowers".
“This battle has been won, but the war continues,” said Mr Assange, who himself has sought refuge from prosecution in the Ecuadorean embassy in London. “The United States can no longer continue the surveillance of world citizens and its digital colonisation of sovereign nations. The public will no longer stand for it.”
US senator Robert Menendez, chairman of the Senate foreign relations committee, described Russia's action as a setback for relations between the countries, while Republican senator John McCain said it was "a deliberate effort to embarrass" the US and a "slap in the face of all Americans".