Syrian regime forces launched a coordinated attack that included about 500 regime troops, 122mm howitzers, tanks and multiple launch rocket systems on the us -backed SDF headquarters in Deir al-Zor province approximately five miles east of the Euphrates River.
Over the weekend, the US struck again, with officials now confirmed that a US MQ-9 Reaper drone attacked and destroyed a Russian T-72 tank in Eastern Syria, in what US officials are claiming was an act of "self-defense".
The Russian Defence Ministry says the incident on February 7 reflects a U.S. push to grab Syria's economic assets under the cover of fighting ISIL.
"We don't have data about other Russians who could be in Syria".
Leviev said his group has confirmed the death of eight Russian private military contractors in the USA strike based on social media.
"If there was a large-scale loss of life of Russian citizens, the relevant officials, including the commander-in-chief of our armed forces (Putin), are obliged to tell the country about it and decide who carries responsibility for this", Yavlinsky said in a statement released by his Yabloko party.
But he would not comment on whether Russian Federation has influence over the forces that did attack.
Lavrov also reiterated that Russian Federation remains in favor of Kurdish participation in the Syrian peace process.
The Americans say their presence in Syria is necessary not only to solve military issues, "but until there is a stable political process there that should end with the transition of power that would be acceptable to all, that is, regime change".
In footage released by the Department of Defense on Tuesday, the T-72 can be seen sitting stationary and appears to fire a round from its 125mm main gun just before being hit by the US air strike that destroyed the vehicle.
Russia's military has said it had nothing to do with the attack and the USA accepted the claim.
Putin's spokesman Dmitry Peskov said the reports needed to be verified.
Their target was a base of the US-backed Syrian Democratic Forces, which came under artillery fire. Utkin was photographed next to President Vladimir Putin at a Kremlin reception in late 2016, held to honor him and others for their service to Russian Federation, for which they have received state awards, according to Peskov.
This incident is not the first time Russian mercenaries have been reported to be operating in Syria. "I advise you to contact the defence ministry".
Mattis, speaking to reporters Tuesday while traveling in Europe, was adamant he knew of no Russian contractors killed in the fighting, which he attributed to a surprising assault in light of obvious USA advantages, including overwhelming air power.
The investigative team said the total number of Russian victims of the airstrike is unlikely to be established, but said 'it is beyond doubt that this incident indeed took place'. "The Russians have always responded to our calls, we always answer".
Wagner, which is under USA sanctions for supporting separatists in eastern Ukraine, has several hundred contractors in Syria, according to analysts.
Some of those Russians killed were said to be mercenaries for the secretive Russian private military group Wagner, which has provided thousands of contract soldiers to help the Assad regime.
There's a refinery in Deir Ezzor that once funded Islamic State operations that's now "crucial" to Assad's plans to finance the reconstruction of Syria once a peace deal is finally reached, according to Yury Barmin, a Middle East analyst at the Russian International Affairs Council in Moscow. He noted that the Russian military could have been unaware of the contractors' involvement in the attacking force because coordination between them has been very poor.