A rift has opened up between NATO allies US and Turkey over the part Syrian Kurdish forces should play in the liberation of Raqqa from Islamic State terrorists as Ankara has openly rejected taking part in any operation that would involve the Kurds.

Turkey has "set out a model" for successfully fighting against jihadists in Syria, which it suggested should be further implemented to defeat Islamic State (IS, formerly ISIS/ISIL) in the region, Turkey's Deputy Prime Minister Numan Kurtulmus said, as cited by Turkish media on Thursday.

Citing the liberation of the cities of al-Bab and Jarabulus in the Aleppo Governorate, which was carried out with the support of the Turkish military, the minister said Ankara was willing to support the anti-terrorist operation to free the IS stronghold of Raqqa in a US-led offensive.

However, Turkey would only fight alongside "moderate opposition" forces in Syria, he added, saying that the participation of Kurdish militants in the international coalition's operation to defeat IS is out of the question for Ankara.

"Turkey will also support such an operation... But if you are saying ‘We will bring in the PYD [Kurdish Democratic Union Party] while taking Daesh [IS] away,' Turkey will never allow it. We will not be involved in such an operation," Kurtulmus told the Anadolu news agency.

Saying that the anti-terrorist operation in Syria is a question of both Turkey's border protection and national security, Kurtulmus added that the issue of the Kurds' participation had been discussed with both the US and Russia.

"If peace is not established in Syria, there will be no regional peace. And if there is no regional peace, there will be no global peace," the official warned.

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Turkey views the Syrian Kurdish Democratic Union Party (PYD) and its militant wing, YPG, which has been a key force fighting Islamic State militants in northern Syria, as linked to the PKK, the Kurdistan Workers’ Party, which operates in Turkey and Iraq. Ankara considers the PKK a terrorist organization and blames it for being behind the Kurdish insurgency in eastern Turkish regions. The US has designated PKK as a terrorist group, while supporting the YPG in Syria. Russia considers neither of the groups to be terrorist.

The Pentagon on Wednesday confirmed that US aircraft airlifted some fighters from Syrian Democratic Forces, a multinational Kurdish-dominated group, in a bid to retake the Tabqa Dam from Islamic State. US forces also provided fire support.

Earlier Wednesday, US Senator John McCain, who heads the Senate Armed Services Committee, said that the Kurdish issue was an "enormous challenge" for Washington in regard to its relations with Ankara.

Saying that the Trump administration is weighing the issue of providing the Kurdish fighters with heavy arms for the anti-IS offensive, the American official admitted the US faces "tough decisions," and should be careful not to cross its NATO ally.

"The conundrum is that if you don't use the Kurds, [the battle against IS] takes a lot longer... But if you do, you have an enormous challenge as far as relations with Turkey are concerned, including things like the use of Incirlik [military base]," McCain told reporters as cited by AFP. The Turkish air base of Incirlik is heavily used by NATO and the US-led coalition to fight Islamic State in the region.

Washington has been long involved in discussions with Ankara on how they "might contribute to the liberation of the city" of Raqqa, but apparently no agreement has yet been reached.

"We haven't come to an agreement about what that role will be or if there will be one, but we talk to Turkey through military channels and I believe at diplomatic levels every day. So, we'll have to let that continue to be worked out," a US Department of Defense spokesperson told the media.