Russian Ambassador to the United States Sergei Kislak said the level of cooperation between the White House and the Kremlin on the Syrian issue was "unprecedented."
"It is very inspirational to see how constructively we can negotiate issues, on which we were far apart six or 12 months ago," he was quoted by Russia's state news agency RIA Novosti as saying Wednesday.
Both sides, he said, were working on ways to address longstanding concerns over nuclear programs in Iran and North Korea.
The United States and Russia are at odds over missile defense issues in Eastern Europe. Moscow says it wants assurances from the U.S. military its strategic interests won't be targeted by the system.
U.S. President Barack Obama canceled a meeting with Russian President Vladimir Putin in August because of concerns over political affairs in Russia and the fallout from the surveillance scandal surrounding Edward Snowden, a former U.S. intelligence analyst granted temporary asylum by the Kremlin.
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