Ras al-Ain (Syria) (AFP) - Kurdish fighters battled to defend a key Syrian border town from Turkish-backed forces on Tuesday as Russia seized on a US withdrawal to move its troops into new areas.
The Damascus regime dispatched more forces to contain the Turkish advance, but its key backer Moscow deployed patrols to prevent clashes between the two sides.
Washington slapped sanctions on its NATO ally in a bid to stop an assault triggered by its own abrupt pullout, but Turkish President Recep Tayyip Erdogan said the operation would continue until "our objectives have been achieved".
US President Donald Trump said he was sending Vice President Mike Pence and Secretary of State Mike Pompeo to Ankara on Wednesday to press for an end to the offensive.
"We are asking for a ceasefire," Trump said. "We put the strongest sanctions that you can imagine."
Britain and Spain joined other major powers in suspending military exports to Turkey.
The Syrian regime's deployment followed a deal announced Sunday between Damascus and the Kurds that saw government troops raise the Syrian flag in the flashpoint northern city of Manbij on Tuesday after US forces withdrew.
Regime troops had entered the city near the Turkish border late Monday, as Turkey-backed fighters massed to the west ahead of a planned assault.
The Kurdish-led Syrian Democratic Forces (SDF) are battling Turkish forces and their Syrian proxies in various parts of the northeast.
East of Manbij, the Kurds are mounting a desperate defence of the border town of Ras al-Ain, using tunnels, berms and trenches.
An AFP correspondent in the area said clashes around the town continued Tuesday, despite Ankara's repeated claims it had captured the area.
The Britain-based Syrian Observatory for Human Rights said Kurdish fighters had launched "a large counterattack against Turkish forces and their Syrian proxies near Ras al-Ain", later reporting "fierce combat" in the west of town as well as in Tal Abyad.
- Erdogan vows to continue -
Since launching their assault on October 9, Turkish-backed forces have secured more than 100 kilometres (60 miles) of border, but Ras al-Ain -- Siri Kani in Kurdish -- has held out.
Trump announced a pullback of US forces from the border last week, a move widely interpreted as green-lighting a long-planned Turkish invasion.
Erdogan, who like Trump faces political difficulties at home, wants to create a buffer zone stretching 30 kilometres (20 miles) from the border into Syrian territory.
He wants to keep at bay the SDF -- seen in Ankara as "terrorists" linked with Kurdish insurgents in Turkey -- as well as resettle some of the 3.6 million Syrian refugees now in Turkey.
"God willing, we will quickly secure the region stretching from Manbij to our border with Iraq," Erdogan said.
The offensive has killed dozens of civilians, mostly on the Kurdish side, and displaced at least 160,000 people.
The UN Security Council will meet Wednesday to discuss the matter.
Aid groups have pulled out international workers and halted work, the Kurds said, but UN agencies continue to operate.
Trump, who is campaigning for re-election but faces impeachment, is keen to deliver on a promise to pull US troops out of Syria.
The United States is to withdraw more than 1,000 troops from northern Syria, keeping only a residual contingent of around 150 at the Al-Tanf base near the southeastern borders with Jordan and Iraq.
Russia said the Syrian army "has full control" of Manbij, and the US-led coalition confirmed its withdrawal.
US troops had been based in the city since helping Kurdish fighters seize it from the Islamic State group in 2016.
Russian military police continue to patrol a zone separating regime troops and Turkish forces, in cooperation with Ankara, Moscow said.
Russia's special envoy on Syria, Alexander Lavrentyev, said Turkish and Syrian officials were in contact to avoid any clashes between Turkish and Syrian forces.
"This would simply be unacceptable," Russian news agencies quoted him as saying.
Turkey has lost six soldiers since the start of the offensive, including two in the Manbij area Tuesday.
- Jihadist breakouts -
Abandoned by the US -- their chief ally in years of battles against IS that saw them lose 11,000 of their fighters -- the Kurds turned to Damascus.
European governments are worried the chaos could trigger mass breakouts by thousands of IS fighters detained by Kurdish forces.
They have warned this could lead to an IS resurgence and increase the risk of some jihadists returning to Europe and conducting attacks.
The Kurds have said hundreds of IS relatives have escaped, although Trump suggested the SDF may have deliberately released them to gain leverage.
At least three French women escapees were "retrieved" by IS, according to messages they sent to their lawyer seen by AFP.
An SDF official on Twitter Tuesday said more IS relatives had tried and failed to escape the overcrowded camped of Al-Hol in eastern Syria.
A US official however told AFP Washington was not aware of any "major" jihadist breakout.