GAZIANTEP, TURKEY - Ankara has warned the United States and Western powers of red lines when it comes to the Kurds and their military advances against Islamic extremists in northern Syria, including a firm position the Kurds must not threaten the territorial integrity of Syria by seeking their own autonomous Kurdish State.

There should also be no demographic changes or population shifts on the Syrian side of the border as a result of Kurdish military offensives against Islamic State, also known as ISIL, according to a policy document approved reportedly by Turkish President Recep Tayyip Erdo?an.

The document was drafted during two high-level security meetings at Turkey’s foreign ministry, after Kurdish fighters captured the Syrian border town of Tal Abyad from Islamic State last week. “No one can act in their own interest just because they are fighting ISIL. The demographic structure of the region cannot be changed through a fait accompli,” states one section of the document leaked to Turkey’s Hürriyet newspaper.

The military gains by fighters from the Kurdish YPG, or People’s Protection Units, which are dominated by Syria’s Democratic Union Party (PYD), are increasingly alarming President Erdo?an. The PYD is an offshoot of Turkey’s own outlawed Kurdistan Workers’ Party (PKK), which has pursued a campaign for Kurdish self-rule since 1984. Peace talks between Ankara and the PKK have stalled.

Kurdish gains

Backed by U.S.-led coalition airstrikes against IS, the Kurds have united two cantons along the border, establishing a contiguous Kurdish region stretching from Kobani in the west to Hasakah Province in the east.

The Turks fear the United States is giving a green light to the Kurds’ post-civil war ambitions. And some analysts agree.

The backing of Kurdish advances with airstrikes “signaled U.S. support for some form of contiguous Kurdish autonomous region in northern Syria, despite continuing Turkish reservations regarding the expansion of YPG influence on its southern border,” argue Christopher Kozak and Genevieve Casagrande, analysts with the Institute for the Study of War, a Washington-backed think tank.

According to the Turkish policy document, Ankara’s alarm has been communicated to Washington, NATO and the U.N. Security Council. “The United States has recognized Turkey’s claim and conveyed it to the PYD administration at the highest level,” the document notes.

But it remains unclear whether the Obama administration at a later stage will support Syrian Kurdish calls for a separate autonomous state or whether it is focused only on the fight against IS.

Last year, when the United States dropped supplies to Kurdish fighters battling to defend the border town of Kobani, U.S. Secretary of State John Kerry said he understood Ankara’s concerns about the PYD’s ties to the PKK.

He appeared to indicate U.S. support for the Syrian Kurds was temporary in nature. “It would be irresponsible of us, as well as morally very difficult, to turn your back on a community fighting ISIL as hard as it is,” he said.

Tal Abyad

On June 11, as Kurdish forces supported by some anti-Assad Arab rebel militias closed in on Tal Abyad, President Erdo?an warned, “The West, which is hitting Arabs and Turkmen of Tal Abyad from the air, is sadly settling the PYD and PKK terror organizations in their places.” On June 14, he said the YPG seizure of Tal Abyad “could lead to the creation of a structure [independent state] that threatens our borders”.

FILE - Syrian refugees, flee intense fighting in n Syrian refugees, flee intense fighting in northern Syria between Kurdish fighters and Islamic State militants, are seen massed at the Turkish border in Akcakale, southeastern Turkey, June 15, 2015. Syrian refugees, flee intense fighting in northern Syria between Kurdish fighters and Islamic State militants, are seen massed at the Turkish border in Akcakale, southeastern Turkey, June 15, 2015.

More than 20,000 people from the mainly Arab town of Tal Abyad and surrounding villages fled over the border into Turkey as the battle between Kurdish fighters and jihadists raged, prompting Turkish government spokesman and Deputy Prime Minister Bulent Arinc to accuse the Kurds of engaging in “ethnic cleansing” in Tal Abyad.

Some Syrian rebel militias fighting to oust Syria’s President Bashar al-Assad have repeated the charge, maintaining the PYD is trying to effect a demographic change along the border to expand Kurdish territory by perpetrating abuses against Arab civilians as they advance, including the burning of Arab homes.

There has been no independent verification of the allegations about Kurdish fighters trying to engineer population shifts along the border, vehemently denied by Syrian Kurds.

PYD leader Salih Müslim, in an interview with CNNTürk, insisted the claim is not true and dismissed the allegation that his fighters are creating a “Kurdish corridor.” “There is no corridor,” he said. “We are fighting against ISIL’s jihadists and the international community sees us as the ones who are the most effective in this fight against the ISIL. And we are satisfied with it.”

He warned, “some circles are trying to ignite a Kurdish-Arab military conflict.”

"Our political stance has been clear in this regard. We have no plan to take a part of Syria. Indeed, we are part of it and we will fight to maintain an independent, democratic and united Syria with our allies,” Zuhat Kobani, a Belgium-based PYD official told VOA Kurdish Service. “Turkey should thank us for what we have done against IS - if it is not supporting this terrorist group.”

The PYD is currently in negotiations with various independent Syrian civil society groups to arrange for them to conduct a fact-finding trip to Tal Abyad and surrounding villages.

But on Monday YPG militias reportedly blocked a fact-finding mission from rebel political factions from entering the town. The Syrian National Coalition, a Western and Gulf-backed umbrella political organization, said a team was refused entry.

"This came after numerous attempts of the committee to enter the town,” the coalition said in a press statement. About 2,000 refugees - 10 percent of those who fled - have been allowed to return.

The allegations of Kurdish territorial ambitions, whether true or not, may complicate the next steps in the Kurdish offensive against IS.

“YPG gains will also likely exacerbate tensions between Syrian Kurds, the Turkish government, and the Assad regime in a way which limits the options available to both the YPG and the United States,” predict Institute for the Study of War analysts Kozak and Casagrande. “These accusations may threaten to disrupt the current cooperation between Kurdish forces and the Syrian opposition during preparations for an offensive on Raqqa city, IS’s de facto capital in Syria."