Raqqa is seen as one of the birthplaces and capital of ISIL’s would-be caliphate, but the pincers are now starting to close on the Syrian city of more than 200,000 people.

US-backed Syrian Democratic Forces, mostly Kurdish fighters, are beginning to approach the outskirts and have taken a number of surrounding villages as they take up positions for a siege.

But the advance is making Turkey nervous.

“We say that every step taken by non-Arab elements as part of the Raqqa operation will be against the interests of the United States. It will be against the peace in the region as well. This is a cul-de-sac. This is the wrong path,” said Deputy Prime Minister Numan Kurtulmus.

The offensive began on Saturday and is getting air support from the US-led coalition, with efforts currently mostly north of Raqqa. Syrian Kurdish leaders have said it should be liberated by Syrian Arab groups, some of whom fight with the Syrian Democratic Forces.