The United States and Turkey on Sunday began joint patrols in northeastern Syria aimed at easing tensions between Ankara and US-backed Kurdish forces who battled the ISIS militant group.
Six Turkish armored vehicles crossed the border to join US forces in Syria for their first joint patrol under a deal reached between Washington and Ankara, AFP reported.
Two helicopters flew over the area as the Turkish vehicles drove through an opening in the concrete wall separating the two countries.
They then headed west along with the same number of American vehicles, along with an ambulance and a pick-up, for the joint operation, before crossing back into Turkey.
The Turkish defense ministry said drones were also deployed.
The agreement reached on August 7 aims to establish a "safe zone" between the Turkish border and the Syrian areas east of the Euphrates river controlled by the Kurdish People's Protection Units (YPG).
Syrian Kurdish forces began withdrawing from along the Turkish border in late August.
Syria condemned on Sunday the joint patrols, saying the move was a “flagrant violation” of its sovereignty, an official statement said.
The move was also a violation of the “territorial integrity” of Syria, said the Syrian foreign ministry statement, referring to what the government considers attempts by the US-backed Kurdish YPG militia to divide the country.
The YPG forms the backbone of the Syrian Democratic Forces -- a key partner of Washington in the fight against ISIS militants in Syria.
But Ankara sees the YPG as an extension of the outlawed Kurdistan Workers' Party.
The PKK, which has waged an insurgency against the Turkish state since 1984, is blacklisted as a terrorist group by Ankara, the US, and the European Union.
Washington's support for the SDF has been a major point of friction with fellow NATO member Turkey.
- 'Preventing war' -
As the regional fight against ISIS winds down, the prospect of a US military withdrawal has stoked Kurdish fears of another Turkish attack.
"We are implementing the agreement and we have no problem with it as long as it prevents war," said Riyad Khamis, the head of an SDF military council in the border town of Tal Abyad.
Although they led the US-backed fight against ISIS, Syria's Kurds have largely stayed out of Syria's eight-year civil war, instead building their own autonomous institutions in areas they control.
But Turkish President Recep Tayyip Erdogan has threatened to launch an operation against the YPG in Syria unless progress is made on setting up the safe zone.
Erdogan said his US counterpart Donald Trump had promised the buffer would be 32 kilometers (20 miles) wide.
Turkish army chief General Yasar Guler told General Joseph Dunford, the top US military officer, in a phone call on Saturday that the safe zone must be set up without delay, the Turkish defense ministry said.
A joint center of operations was recently established as part of the agreement.
Turkey carried out unilateral offensives in northern Syria against ISIS in 2016 and the YPG in 2018.
Ankara hopes the safe zone will smooth the way for the return of some of the more than 3.6 million Syrian refugees living in Turkey, but experts say the situation remains unclear.
"We may have joint patrols but we still don't have a joint understanding of what the safe zone is," said Nicholas Danforth, senior visiting fellow at the German Marshall Fund of the United States.
"America sees the safe zone as a way to preserve our relationship with the SDF and preserve the SDF's autonomy. Turkey sees the safe zone as a step toward ending them both.
