The Russian military announced Tuesday that its troops are patrolling the Syrian-Turkey border town of Manbij, immediately backfilling a vacuum left by U.S. troops who departed on Monday.

Russian military police were patrolling “along the line of contact between the Syrian Arab Republic and Turkey,” the Russian Defense Ministry said in a statement, and are “interacting” with Turkey, which last week launched a ground and air assault on U.S.-backed Kurdish fighters in northeastern Syria.

A spokesman for the U.S. counter-ISIS coalition confirmed Tuesday morning that all American troops have left Manbij.

At the same time, the Kurdish fighters under assault by Turkey moved Monday to strike a deal with Syrian President Bashar al-Assad’s government to help defend against the Turkish offensive. Russia, vying for influence in wartorn Syria, has backed Assad’s regime for four years with punishing airstrikes on opposition forces.

Russian state media on Monday issued a trolling message that purported to show a U.S. convoy and Syrian Army forces passing one another on the road out of the border town of Kobani, with the Americans on the way out and the Syrian Army forces on the way in. “Wondering if they waved to each other…” the tweet read.

The head-spinning developments show how quickly Russia has moved to take advantage of President Trump’s precipitous withdrawal from northeastern Syria, announced in rapidly escalating stages over the last week. The White House announced on Oct. 6 that U.S. special operators patrolling a negotiated border zone with Turkey would withdraw ahead of a threatened Turkish advance and within three days, Turkish President Recep Tayyip Erdogan had launched the first airstrikes. Over the weekend, Trump announced a full U.S. withdrawal of the remaining thousand troops from Syria, leaving behind the Kurdish fighters who have been battling ISIS with U.S. direction and backing for four years — while also fending off Assad’s forces.

"After the Americans abandoned the region and gave the green light for the Turkish attack, we were forced to explore another option, which is talks with Damascus and Moscow to find a way out and thwart these Turkish attacks," senior Kurdish official Badran Jia Kurd told reporters. "This is a preliminary military agreement. The political aspects were not discussed, and these will be discussed at later stages.”

Turkey says its offensive is intended to clear northeastern Syria of fighters formerly backed by the U.S. that Ankara considers to be terrorists — they are led by a faction of a Kudish separatist group Turkey — and to create space to rehome Syrian refugees currently living in Turkey.

Trump has signalled that he had no concerns about the rapidly shifting mosaic of alliances in Syria that critics say is wholesale ceding influence to Moscow in the region.

"Anyone who wants to assist Syria in protecting the Kurds is good with me, whether it is Russia, China, or Napoleon Bonaparte. I hope they all do great, we are 7,000 miles away!” Trump tweeted on Monday.

“After defeating 100% of the ISIS Caliphate, I largely moved our troops out of Syria. Let Syria and Assad protect the Kurds and fight Turkey for their own land. I said to my Generals, why should we be fighting for Syria,” he said in another message.

Senior U.S. officials have sought to place the blame for the abrupt conflagration of a delicately stable northeastern Syria solely on Turkey, denying that Trump’s withdrawal gave Turkey a “green light” to attack. Defense Secretary Mark Esper said Tuesday morning that he will travel to NATO next week to rally U.S. allies to take “collective and individual diplomatic and economic measures in response to these egregious Turkish actions.”

The fighting has already taken a devastating toll on the local population. According to the United Nations, as many as 160,000 people have been displaced since the fighting began last week.