The U.S.-backed Syrian Democratic Forces said Tuesday they would coordinate with Syrian government troops to fend off any Turkish invasion of the north and protect Syrian territory.
They said the decision came after an emergency meeting of their top commanders that discussed threats by Turkey to wage a new offensive on swathes of northern Syria they control.
Meanwhile, Russia and Syrian government forces have been bolstered in northern Syria where Turkey may soon launch an offensive against Kurdish fighters, Turkish and rebel Syrian officials said, as Ankara prepares for talks with Moscow.
President Recep Tayyip Erdogan said two weeks ago Turkey would launch new military operations in Syria to extend 30-km (20-mile) deep "safe zones" along the border, aiming at the Tal Rifaat and Manbij regions and other areas further east.
Russia, which warned at the weekend against military escalation in northern Syria, is sending Foreign Minister Sergey Lavrov for talks in Ankara on Wednesday.
The two countries have close ties, and Ankara has sought to mediate talks over Russia's war in Ukraine, but their support for opposing sides in Syria may test President Vladimir Putin's relations with the only NATO member not to impose sanctions on Moscow over the invasion.
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The stakes are also high for Erdogan. Without at least tacit approval from Russia, President Bashar al-Assad's powerful ally in the Syria conflict, a Turkish offensive would carry additional risk of casualties. Russia and Turkey have checked each other's military ambitions at various points in Syria's war, at times bringing them close to direct confrontation.
There have not yet been signs of a significant Turkish military build-up in the border region but reports of rocket and artillery exchanges have become more frequent in the past two weeks.
Any Turkish operation would attack the Kurdish YPG militia, a key part of the U.S.-backed Syrian Democratic Forces (SDF) that controls large parts of north Syria and is regarded by Washington as an important ally against Islamic State. Ankara sees it as a terrorist group and extension of the militant Kurdistan Workers Party (PKK).
A spokesman for the Turkey-backed Syrian National Army (SNA) said Russia was reinforcing positions near Tal Rifaat, Manbij, the southern outskirts of Kobani, and Ain Issa - all towns within 40 kilometers of the Turkish border.
"Since the announcement of the operation, the Syrian regime and its Iranian militias have mobilized and [are] sending reinforcements to the YPG," Major Youssef Hammoud told Reuters.
Their intelligence had spotted Russian helicopters landing at an air base close to Tal Rifaat, he added.
Turkey's state-owned Anadolu news agency cited local sources on Saturday as saying Russia was making deployments in north Syria to "consolidate its control," flying reconnaissance flights over Tal Rifaat and setting up Pantsir-S1 air defense systems in Qamishli, a border town nearly 400 kilometers further east.
SDF commander Mazloum Abdi told Reuters on Sunday Damascus should use its air defense systems against Turkish planes and his forces were "open" to working with Syrian troops to fight off Turkey but said there was no need to send more forces.
Talks with Lavrov
Ankara says it must act because Washington and Moscow broke promises to push the YPG 30 kilometers from the border after a 2019 Turkish offensive. With both powers seeking Turkey's support over Ukraine, the conflict may offer it a degree of leverage.
Washington, whose backing for the SDF has long been a source of strain in ties with Turkey, has voiced concern, saying any new operation would put at risk U.S. troops — which have a presence in Syria — and undermine regional stability.
Russia also said last week it hoped Turkey "refrains from actions which could lead to a dangerous deterioration of the already difficult situation in Syria."
A senior Turkish official said Lavrov would be asked about intelligence that he said pointed to Syrian government and Iran-backed forces either arriving at Tal Rifaat or heading there.
"Turkey will do this operation one way or another," the official said, speaking on condition of anonymity.
Asked whether Russia was strengthening positions in northern Syria, Kremlin spokesman Dmitry Peskov told reporters it was the Syrian armed forces that "are reinforcing, to a greater or lesser extent, certain facilities on their territory."
The Syrian government does not comment on troop movements, but the pro-government newspaper al-Watan on Monday cited sources in northern Raqqa — near the Turkish border — as saying Syrian troops, tanks and heavy weaponry deployed over the weekend in response to Turkish moves.
The Turkish official and the SNA's Hammoud said attacks from SDF-controlled areas against those under Turkish and SNA control had increased. Hammoud said Turkish and SNA forces were responding.