Several Russians killed in USA airstrikes in Syria, friends say

Russian army servicemen at the Khmeimim Air Base in Syria

Earlier, the U.S. military said that it killed more than 100 Syrian militiamen allied with the government of President Bashar Assad after some 500 fighters targeted "well-established Syrian Democratic Forces headquarters" in Deir al-Zor province in what the Pentagon called an "unprovoked attack".

The convoluted fighting in Syria pits the USA and Russian Federation on opposite sides, and a recent battle has resulted in this jarring description from Bloomberg: It may have been "the deadliest clash between citizens of the former foes since the Cold War". Defense Secretary Jim Mattis has called the whole thing "perplexing", but provided no further details.

Kremlin spokesman Dmitry Peskov, speaking on a conference call with reporters, said he had no information about any such casualties.

The Russian Defense Ministry said its troops weren't involved in the operation. "But Russia will pretend nothing happened".

"The tank had been maneuvering with coordinated indirect fire on a defensive position occupied by Syrian Democratic Forces and Coalition advisers", said US Marine Corps Maj.

As the Islamic State's dominance in the region has been decimated, state actors have entered the fill the power vacuum.

Last month, Russian Federation signed an energy agreement with Syria pledging to rebuild the country's electricity infrastructure.

American forces in Syria reportedly killed more than 100 Russian mercenaries fighting on behalf of the pro-regime military in what could have been the deadliest clash between the two nations since the Cold War.

It has stressed repeatedly since February 7 that no members of the Russian armed forces were killed and that any Russians fighting alongside the Syrians were mercenaries. According to reports, Coalition and SDF troops recovered three bodies from the tank.

The base was defended by American and Kurdish troops, who reportedly called in a USA -led airstrike as their position came under attack.

The Kremlin on Wednesday said it could not rule out that there were Russians in Syria, but that if so, they had no affiliation with Russian armed forces. Alexander Averin, a member of the Other Russia nationalist party, confirmed that Kirill Ananiev, a party member who left for Syria about a year ago, had been killed in the airstrike, noting that there were other "substantial losses".

No US casualties were reported.

Last week, Mattis dismissed any suggestion that Russian Federation has any control over the attacking force.

"Coalition officials maintained regular contact with Russian counterparts via established deconfliction lines to avoid misperceptions and miscalculations that could endanger each other's forces".

Harrigan said the attacking forces were fighting on the side of Bashar al-Assad's regime, but said he would "not speculate on the composition of this force, or whose control they were under". The fighters had no air cover or mobile air defense to protect them during the fighting, they said.

Also on Tuesday, Russian Foreign Minister Sergei Lavrov said the United States was acting in a "dangerous way", undermining Syria's integrity through unilateral actions.

Syrian government forces in Deir Ezzor.