Turkish Prime Minister Binali Yildirim has warned of a major damage to US relations with Ankara if Washington includes Kurdish forces in the operation to retake Syrian city of Raqqah from Daesh.
Yildirim told the Associated Press on Thursday that Turkey will not be part of any mission that includes the Kurdish People's Protection Units (YPG).
"If the US were to prefer terrorist organizations over Turkey in the fight against Daesh, that would be their own decision, but that wouldn't be something we would consent" to, he added.
Ankara views the YPG as a terrorist organization because of its alleged links to the outlawed Kurdistan Workers’ Party (PKK), but Washington regards the YPG as an ally in Syria.
Yildirim said Turkey was still awaiting a US decision on Raqqah amid signs that such a decision could come soon.
Turkish officials had signaled before that they could deny US access to the Incirlik Air Base unless Washington halted its support for Syria's Kurdish militants.
On Thursday, separate reports said a US Marines artillery unit had been deployed to Syria in recent days in preparation for the capture of Raqqah.
US Air Force Colonel John Dorrian said the deployment, comprising a total of 400 American forces, added to around 500 US military personnel already stationed in Syria.
The US and Turkey have deployed troops without permission from the Syrian government or a UN mandate, further complicating the convoluted situation in the Arab country which is plagued by terrorism.
Turkey threatens to hit Kurdish forces in Manbij
On Thursday, Turkey threatened to strike Kurdish forces operating in the northern Syrian city of Manbij if they maintain their presence there in the face of advances by Turkish troops.
Turkey's NTV quoted Foreign Minister Mevlut Cavusoglu as warning of the threat posed by the YPG as well as its military wing, the Democratic Union Party (PYD), to the country.
"The PYD is as dangerous for our security as Daesh,” Cavusoglu said. Turkey “will not allow the YPG's canton dreams (to come true),” he said, adding, “If we go to Manbij and the PYD is there, we will hit them.”
The so-called Syria Democratic Forces (SDF), which is led by the YPG, captured Manbij in August 2016 with the help of the US military.
Earlier this week, the Pentagon announced that the US had deployed a small number of forces in and around Manbij in an attempt to prevent clashes between the Turkey- and US-backed forces active in the area.
The deployment was the first of its kind by the US in Manbij. American forces have carried out training and advising missions in the city.
Cavusoglu said Washington appears confused in its planning for an attack on Raqqa. Turkish President Recep Tayyip Erdogan's spokesman Ibrahim Kalin said the YPG should move out of Manbij to the eastern side of the Euphrates River.
Kalin further stressed that no decision had yet been taken on who carries out the Raqqah operation.
Turkey is one of the key countries in the Syria conflict, which has raged on since March 2011, allowing militants from around the world to freely enter the Arab nation and wreak havoc there.
Turkey also launched its incursion into Syria in August 2016 in an alleged bid to push Daesh from Turkey's border with Syria and stop the advance of Kurdish forces.
Turkey should not be allowed to occupy Syria: SDF
On Thursday, the SDF said it had told US Senator John McCain and US military officials in northern Syria last month that Turkey must not be involved in the Raqqah campaign.
"The Turkish side is an occupation force and it cannot be allowed to occupy more Syrian land," SDF spokesman Talal Silo told Reuters.
Silo also said the SDF would reach the outskirts of Raqqah “within a few weeks” after severing the last main road to the city this week.