Russia is already by far the strongest foreign power operating in Syria, and President Vladimir Putin has allied himself with Syrian President Bashar al-Assad, throwing the full weight of the Russian military behind the Syrian Army.
Now, a planned Turkish operation to "clear" Kurdish forces from the Northeastern Syrian border zone could give Putin a chance to expand Russian influence -- to the alarrm of US hawks.
Russia's footprint in Syria
Russia's main base in Syria is the airfield at Hmeimin on the Mediterranean coast, close to the city of Latakia. It's more than just an airbase: Much of Russia's senior military personnel running the Syria campaign are also stationed there. The base also houses the Russian army's deconfliction center, which communicated with the US-led coalition to keep the two sides' warplanes out of each others' ways.
Further south, Syria's port of Tartus holds Moscow's main naval base, and its only base in the Mediterranean Sea. Russian submarines and warships equipped with cruise missiles often fired at ISIS and anti-Assad rebel groups when combat in Syria was still intense. At the height of the Syrian conflict, Russia also had a substantial presence of ground forces in the country. It appears to have withdrawn some of those troops as combat operations wound down.
And on top of its military presence in Syria, Moscow is also making economic moves in Syria. Russian oil and gas firms have gained contracts for the exploitation of hydrocarbons in Eastern Syria.
How Russia sees the US withdrawal
Russia wants the US to leave Syria, and has repeatedly stated that it believes the US is in Syria illegally.
On Wednesday, Russian foreign minister Sergey Lavrov said he still did not believe that Trump would follow through on his announcement to withdraw US forces. "Donald Trump has indeed stated many times that he will withdraw his troops from Syria and from other countries. Then actual doers put brakes on this. I do not exclude that we are now observing something similar," Lavrov said at an event in the Kazakh capital Nur-Sultan.
Russia supports the disputed Syrian government, while Turkey backs one of Syria's main rebel groups. Though Russia and Turkey support opposing sides in the Syrian civil war, Russia would certainly welcome a full US withdrawal from Syria because it would give Moscow even more leverage -- not just in shaping Syria's future, but across the entire Middle.
Would Russia support a Turkish invasion?
Turkey plans to enter Syria and drive back Kurdish fighters from a large swathe of land near the border. While Turkey has become an ever more important partner for Russia both in Syria and on the international political stage, Russia does not appear to endorse Turkey's announced military operations.
The reason for this simple: As an ally of the Assad government, Russia's stated goal is winning back all of Syria's territory from rebels and pro-US forces, and Turkey's cross-border operation could become a longer-term breach of territorial sovereignty.
On Wednesday, Damascus blasted Turkey's announcement that it wants to move troops into Syria. "The aggressive behavior of the Erdogan regime clearly shows the Turkish expansionist ambitions in the territory of the Syrian Arab Republic and cannot be justified under any pretext," a statement from Syria's foreign ministry said.
But Russia is also keen to cater to its Turkish allies, and has offered to negotiate with all sides for a solution. "We are in touch with both the representatives of the Kurdish side and the representatives of the government, and we are encouraging them to start a dialogue to resolve the problems of this part of Syria, including the problems of ensuring security on the Turkish-Syrian border," Foreign Minister Sergey Lavrov said.
But can Russia deliver?
Russia could not stop Turkey from moving into Northern Syria and ousting Kurdish forces -- but it could potentially reduce the bloodshed through mediation.
Putin spoke with Recep Tayyip Erdogan on Wednesday, and the Turkish President seemed to indicate that it was only a matter of when -- not if -- his forces would cross the Syrian border. According to Turkey's Anadolu news agency, Erdogan told Putin that the military operation would contribute to peace and stability in Syria, and pave the way for political process in the country.
However, Putin could prevent a larger bloodbath. The formerly US-aligned Kurdish forces which the Turks are trying to "clear" from the area are not against the Syrian government and not against Russia either.
In fact Kurdish fighters from the same organization fighting on America's side against ISIS have also fought on the side of Russia and the Syrian government. During the Battle of Aleppo, they fought against anti-Assad rebels. The Russians and the Syrian government have always maintained contact with the Kurds, in hopes of getting them to submit to Syrian government rule, and the Syrian Army maintains a presence in the Kurdish-held areas.
Now Russia's moment may have arrived. Moscow wields influence with Ankara, Damascus and the Kurds. A statement from the Kurdish-led authorities on Wednesday seemed telling, the saying they welcomed statements by Russia's foreign minister and hoped that Russia would play a role in de-escalating the situation.
US concerns over Russia's role
Critics of Trump's decision to withdraw from Syria have pointed specifically to Russia's expanding influence as a concern
"A precipitous withdrawal of US forces from Syria would only benefit Russia, Iran, and the Assad regime," tweeted US Senate Majority Leader Mitch McConnell, usually a staunch Trump ally and one of the most vocal critics of the pull-back.