US Secretary of State Antony Blinken warned Nato ally Turkey on Wednesday against carrying out a military offensive in Syria, saying it would put the region at risk.
Mr Blinken urged Turkey to stick to ceasefire lines established in 2019 after President Recep Tayyip Erdogan renewed threats to “clean up” two northern Syrian cities of Kurdish fighters.
“It's something that we would oppose,” the top US diplomat told a joint news alongside Nato Secretary General Jens Stoltenberg in Washington.
“The concern that we have is that any new offensive would undermine regional stability [and] provide malign actors with opportunities to exploit instability.”
The US has partnered with the Syrian Democratic Forces (SDF), a majority-Kurdish fighting force, to defeat ISIS in war-battered Syria.
But Turkey considers the Syrian-Kurdish fighters to be part of the PKK, a separatist organisation labelled a terrorist group by Ankara.
“We continue effectively to take the fight through partners to … ISIS within Syria and we don't want to see anything that jeopardises the efforts that are made to continue to keep ISIS in the box that we put it in,” Mr Blinken said.
On Wednesday in Ankara, Mr Erdogan said Turkey would rid northern Syria's Tal Rifaat and Manbij areas of “terrorists”, confirming the targets of the new incursion for the first time and saying the offensive would continue into other regions.
His comments, made in a speech to members of his ruling AKP, came after he pledged to engage in a new military incursion on Turkey's southern border.
“We are going into the new phase of our determination to form a 30-kilometre deep safe zone along our southern border. We will clear Tal Rifaat and Manbij of terrorists, and we will do the same to other regions step-by-step,” he said.
“Let's see who supports these legitimate steps by Turkey and who hinders them,” Mr Erdogan added.
The SDF said that such an operation would suspend the fight against ISIS.
“The SDF has been expecting a possible battle for a while now,” said Farhad Shami, a spokesman for the Kurdish-led force.
“In the event of an attack, we will pause our war against [ISIS] and start military measures against the Turkish invasion,” he told AFP.