Turkey has said it sent troops into Idlib province to help establish a de-escalation zone in line with the Astana agreement. Syria has rejected that claim, saying the presence of Turkish troops was at odds with the deal.
Syria's Foreign Ministry demanded Turkey immediately withdraw its troops Saturday, calling their presence in northwestern Syria a "flagrant aggression."
Turkish troops entered Idlib province Thursday night in an attempt to enforce a so-called "de-escalation zone" that Ankara said was agreed to at the Astana summit with Russia, Iran and Turkey in the Kazakhstan capital in May.
But the Syrian government slammed Turkey's incursion and rejected the claim that Turkish troops in Syria could be construed to be in line with the Astana agreement.
"Syria condemns in the strongest terms the incursion of units of the Turkish army in Idlib province, which constitutes a flagrant aggression against the sovereignty and security of Syrian territory," the Foreign Ministry's statement said.
It went on to say that "The Turkish aggression is not tied in any way with the understandings that were reached between the guarantor states in the Astana process, but constitutes a violation of these understandings."
An unnamed source at Syria's Foreign Ministry said, "The Turkish regime must abide by what was agreed in Astana."
Turkey's military said Friday it had begun "activities to establish observation posts on October 12," days after its troops began a reconnaissance mission in Idlib.
Friday, Turkey's Hurriyet daily reported more than 100 Turkish soldiers, including Special Forces, and 30 armored vehicles, had entered Idlib.
Beyond government control
Another Turkish convoy reportedly entered on Saturday, according to the Syrian Observatory for Human Rights, a UK-based monitoring organization.
Idlib is primarily under control by Hayat Tahrir al-Sham (HTS), a group led by al Qaeda's former Syria affiliate, which in recent months has succeeded in fighting against more moderate rebel groups.
Turkish President Recep Tayyip Erdogan said his troops had entered Syria with the Free Syrian Army, the name Ankara uses for rebels seeking to topple Syrian President Bashar al-Assad.
Turkey said it's backing the Syrian rebels in an attempt to oust HTS members in the area and allow Iranian, Russian and Turkish forces to implement the de-escalation zone.
The Idlib de-escalation zone is one of four agreed to in Astana and the last one to be implemented.
Idlib remains one of the few major areas in Syria still beyond the government's control. With the help of Russian air power, Syrian troops have regained swathes the country over the past two years.
This is not the first time Turkey has intervened in Syria. Last year it launched operation Euphrates Shield, targeting the Islamic State militants and Kurdish fighters.
Syria's descent into a brutal war began in March 2011 with anti-government demonstrations. Since then more than 330,000 people have been killed.
bik/sms (Reuters, AFP)