The head of a US-backed Kurdish militant group fighting in Syria says a confrontation is likely “within days” between his fighters and the Turkish forces recently deployed to Syria’s Aleppo Province.

“These [Turkish military] preparations have reached level of a declaration of war and could lead to the outbreak of actual clashes in the coming days. We will not stand idly by against this potential aggression,” said Sipan Hemo, the commander of Syrian Kurdish People’s Protection Units (YPG), told Reuters on Wednesday.

Turkey and Kurds harbor historical hostilities toward one another. Ankara considers Kurdish populations, whether in Syria, Iraq, or Turkey itself, as “terrorist” groups bent on taking away territory from Turkish soil.

The YPG fighters have been involved in a major attack against Takfiri Daesh terrorists in Syria’s northern city of Raqqah since June. And Turkey has deployed forces to Syria without obtaining a permission from the Syrian government.

The YPG is part of a larger coalition of fighters — the so-called Syrian Democratic Forces (SDF) — which has been engaged in operations aimed at liberating Raqqah. The US considers the SDF, which also includes Arab fighters, as its main proxy force fighting on the ground in Syria.

Ankara has already expressed its deep concern about the advancement of YPG forces in northern Syria.

Hemo indicated that the YPG would continue to fight Daesh terrorists even after their defeat in Raqqah, saying it was committed with “the international coalition to cleansing Syria of terrorism,” referring to a US-led coalition carrying out aerial bombardment against purported Daesh positions in Syria.

The US’s provision of weapons to the YPG has further incensed Turkey, a NATO member, prompting Turkish President Recep Tayyip Erdogan to warn the White House about the purported consequences of arming the “terrorist” YPG.

In an attempt to address Turkish concerns, the US said last month that it would have the Kurdish fighters in Syria disarmed once Daesh has been flushed out of Raqqah. Turkey wasn’t impressed. Turkish Deputy Prime Minister Numan Kurtulmus said on Wednesday that no group armed in the Middle East had ever returned the weapons it had received.

Washington has “formed more than a terrorist organization there, they formed a small-scale army,” he said.

Kurtulmus also retorted that Hemo’s claims about a declaration of war by Ankara was not true, saying that his country would however respond to any hostile move by the YPG.

“This is not a declaration of war. We are making preparations against potential threats. Their (YPG) primary goal is a threat to Turkey, and if Turkey sees a YPG movement in northern Syria that is a threat to it, it will retaliate in kind,” Kurtulmus said.

Ankara fears that the YPG will permanently hold parts of land in northern Syria after Daesh is routed.

Referring to that possibility, President Erdogan said recently, “I want the entire world to know that in northern Syria, on our border, we are never going to allow a terrorist state to be established.”

In a bid to keep the Kurds far from Turkey’s southern border, the Turkish government has also been training armed men affiliated with the so-called Free Syrian Army (FSA) to fight Kurdish forces for some time.

“If there is a threat against us, our troops will conduct any operations with the Free Syrian Army (FSA) on the ground,” Erdogan announced in an interview with France 24 television aired on Wednesday.

Last week, however, Hemo said that the YPG had never “threatened Turkey or its security,” while slamming the Turkish intervention in Syria as “occupation” of Syrian territory. He also said that the Kurdish fighters under his command planned to capture an area between the northwestern border towns of A’zaz and Jarablus, both of which are currently under the control of Turkey-backed FSA militiamen.

In separate comments made in an interview with the Saudi-owned Asharq al-Awsat daily published on Wednesday, Hemo also said that Washington has already set up seven military bases in Syria’s northern areas, which are controlled by the YPG or SDF, including a major airbase in the vicinity of Kobani, a town at the border with Turkey.

The city of Raqqah, which lies on the northern bank of the Euphrates River, was overrun by Daesh terrorists in March 2013.