"Turkish regime forces targeted the locations of popular forces with artillery fire as they arrived to the Afrin region," Syria’s state news agency SANA reported on Tuesday.
On Tuesday afternoon, hundreds of popular forces from the National Defense Forces (NDF) supporting the government in Damascus began entering the Kurdish-held region of Afrin through the al-Ziyara crossing point north of the town of Nubl.
Turkish state news agency Anadolu said Turkey’s army fired "warning shots" at the Syrian popular forces, noting that they “retreated to about 10 kilometers from the town because of the warning shots."
The shelling marks a major escalation of tensions between the two countries since Turkey and its allied militants launched a military offensive against Afrin last month.
In a statement on Tuesday, US-backed People's Protection Units (YPG) spokesman Nouri Mahmoud said the Kurdish forces had called on the Syrian government to help fend off Turkey's assault.
"The Syrian government responded to the invitation, answered the call of duty and sent military units today, February 20, to take up positions on the borders, and participate in defending the territorial unity of Syria and its borders," the statement said.
This is the first time that Syrian government forces are deployed in the area since 2012 when the YPG held the area under its control.
Meanwhile, Turkish media say Turkey’s army and its allied Syrian opposition militants are advancing in Afrin and they have reportedly taken over a key road linking the Turkish-held town of Azaz to the city of Afrin. Turkish forces are in control of nine more villages in the region.
Earlier on Tuesday, Turkish President Recep Tayyip Erdogan said the country is set to “lay siege” to Afrin, noting that the siege will prevent YPG militants from “bargaining” with the Syrian government.
