US officials have denied Kremlin allegations that Syrian rebels were using US stingers or other US-made surface-to-air missiles in the Syrian civil war.
A Russian general claimed he had "reliable information" that the Free Syrian Army was using the anti-aircraft weapon in its fight against the regime led by Bashar al-Assad.
"We have reliable information that Syrian militants have foreign portable anti-aircraft missile systems, including those made in the USA." Gen Nikolai Makarov told news agency Interfax
The US supplied Stingers to the mujahedeen in the 1980s during the Soviet invasion of Afghanistan and turned the course of the war.
But US State Department spokesperson Victoria Nuland denied Makarov's claims.
"We are providing no lethal assistance to the Syrians. We have provided no Stingers of any kind to Syria, nor will we," she said.
"If the Russian Federation has evidence of Stingers in the hands of the opposition, we'd like to see it."
Nuland said that according to the State Department, all anti-aircraft weaponry on Syrian soil was of Soviet origin.
"All the images we've seen of Manpads [Man-portable air-defence systems] and Manpad-like equipment in Syria have been exclusively of a Soviet Warsaw Pact vintage - the SA-7 type vintage," she said.
According to the Moscow Times, in the last year Russia has sold to Assad's government $1bn worth of weapons.
Human Rights Watch has reported that the Assad regime was using Soviet-made cluster bombs against its population.
Fighting between the two main sides in Syria continues to seesaw with Syrian rebels claiming a recent victory by shooting down an army helicopter, which exploded on impact.
A video of the copter spiralling to the ground was posted on the internet.