The White House has threatened to pull out of a summit with Vladimir Putin in retaliation for Russia's decision to grant asylum to Edward Snowden, the fugitive whistleblower.
Spokesman Jay Carney said the Obama Administration was "evaluating the utility" of a scheduled summit with Putin in Moscow next month in advance of a G20 meeting in St Petersburg.
"We are extremely disappointed that the Russian Government would take this step despite our very clear and lawful requests in public and private that Mr Snowden be expelled and returned to the United States," said Carney.
Senator Chuck Schumer, a New York Democrat, declared: "Russia's stabbed us in the back, and every day that Snowden is allowed to be free they twist the knife further. Now that Snowden has been set free, I don't think the G20 should be meeting in Russia and I think we should not participate if they do."
Moscow granted Snowden one year's temporary asylum in Russia, ending nearly five weeks of limbo in a Moscow airport and infuriating the White House.