The Syrian government announced Friday that its troops had entered the northeastern city of Manbij in an apparent bid to forestall a Turkish invasion aimed at driving out the Syrian Kurdish YPG militia.

The YPG, which has served as the Pentagon’s principal proxy ground force in controlling nearly a third of the Syrian territory near the Turkish border, is regarded by the government of President Recep Tayyip Erdogan as a branch of the Turkish Kurdish PKK, against which Turkey’s security forces have waged a bloody, decades-long counterinsurgency operation.

Erdogan vowed earlier this month that the Turkish military would intervene to push the YPG back from the border. US President Donald Trump’s December 19 announcement that he was ordering the withdrawal of all 2,000-plus US troops from Syria and leaving the military campaign against the Islamic State of Iraq and Syria (ISIS) in Ankara’s hands appeared to open the door to a Turkish intervention and a broader scramble for control of northeastern Syria, which consists largely of sparsely populated desert, but also contains the country’s main oil and natural gas reserves.

In a statement posted on Twitter, the YPG said that it had invited the Syrian government of President Bashar al-Assad “to send its armed forces to take over these positions and protect Manbij in the face of Turkish threats.” The tweet, which was sent in the morning, was subsequently deleted and then reposted later in the day, likely reflecting the tensions between the YPG and its US military patrons following Trump’s announcement.

While the Syrian government issued a statement saying that its troops had entered Manbij, a city of approximately 100,000, and hoisted the national flag, the US military, which still has special operations units based near the city, as well as some local residents speaking to the Western media denied that the Syrian army was deployed in the city.

Other reports indicate that the Syrian military has doubled the number of troops that had already taken up positions on the city’s outskirts and has deployed them between the Turkish and Kurdish forces.

Manbij fell to US and Turkish-backed “rebels” in 2012, including the Al Qaeda-linked Al Nusra Front, and was subsequently overrun by ISIS in 2014. In the summer of 2016 the so-called Syrian Democratic Forces, the YPG-dominated US ground proxy force, took control of the city.

The Turkish military has massed troops, tanks and armored personnel carriers on the border near Manbij in recent days, while Reuters quoted the main Turkish-backed Syrian “rebel” group, the “Free Syrian Army,” as stating on Friday that it had sent convoys, together with Turkish forces, toward the frontlines with Manbij, in “full readiness … to start military operations to liberate” the city. An FSA commander said that the group had 15,000 fighters prepared to attack the city.

Turkey carried out a similar operation in March of this year against the predominantly Kurdish town of Afrin, west of the Euphrates River, forcing over 200,000 people to flee their homes. Since then, Ankara has given free rein to the so-called “rebels” to carry out looting, arbitrary detentions, torture and killings, according to human rights groups.

Erdogan responded to the report of the movement of Syrian government forces to Manbij by calling it a “psychological” operation, amounting to “waving their own flag there.” He said that Damascus carried out a similar action in Afrin before the Turkish invasion.

He added that “It’s not just about Manbij, we are aiming to wipe out all terrorist organizations in the region. Our main target is that the YPG takes the necessary lessons here.”

The Trump White House appears prepared to sacrifice its erstwhile Kurdish proxy force in the interests of repairing ties with Ankara. Relations between the two NATO allies have been strained since an abortive July 2016 military coup against Erdogan that enjoyed US backing and had further deteriorated over the Pentagon’s alliance with the YPG.

Among Washington’s objectives is undoubtedly driving a wedge between Turkey and Russia, which have established closer ties as relations between Washington and Ankara soured. Turkey has collaborated with Russia and Iran in the so-called Astana peace process for Syria, which has eclipsed the Geneva talks backed by the US.

A delegation from Turkey consisting of its foreign minister, Mevlüt Çavuşoğlu, and defense minister, Hulusi Akar, along with other officials, is due to arrive in Moscow today to discuss with their Russian counterparts the implications of the US troop withdrawal.

The precise timetable and conditions for the US troop withdrawal remain far from clear. On December 23, Trump tweeted that he had discussed with Erdogan a “slow and highly coordinated pullout of U.S. troops from the area” of northeastern Syria.

At the same time, during his December 26 lightning visit to the Pentagon’s Al Asad airbase in western Iraq, the US president declared that American troops were in Iraq to stay—despite the overwhelming hostility to their presence among the Iraqi people—and that the base could be used to carry out cross-border raids into Syria.

The clear suggestion was that US special operations troops will continue to operate in northeastern Syria. Whether their operations are directed at suppressing ISIS or reviving it for use against the Syrian government remains to be seen.

The US State Department, meanwhile, issued a ringing endorsement Friday of Israeli air strikes carried out against alleged Iranian-tied targets inside Syria. The Israeli military has acknowledged carrying out over 200 such strikes since 2017.

“Iranian support of and supply to terrorist groups in Syria and across the region that have the clear intent and capability to strike Israel are unacceptable,” the State Department said. “The United States fully supports Israel’s right to defend itself against the Iranian regime’s aggressive adventurism, and we will continue to ensure that Israel has the military capacity to do so decisively.”

The statement came just three days after Israeli strikes on targets in Syria that were denounced by Moscow as “a gross violation of the sovereignty of Syria” that also threatened two civilian passenger planes.

Whatever the tactical shift carried out by the Trump administration in relation to US troop deployments in Syria, it is clear that Washington is continuing its strategy of military aggression aimed at asserting US hegemony—and rolling back Iranian and Russian influence—in Syria and the entire oil-rich Middle East. The threat that these efforts will spill over into a regionwide and even world war have in no way been lessened.