Pro-government fighters have entered the Kurdish-held enclave of Afrin in northern Syria, triggering an immediate response from Turkish forces.
The main Syrian Kurdish militia, the People's Protection Units (YPG), said in a statement on February 20 that Syria's government had sent "military units" to Afrin to deploy along the border with Turkey and help repel an offensive by Turkish troops and allied Syrian rebels.
They will "take up positions on the borders, and participate in defending the territorial unity of Syria and its borders," a statement said.
Meanwhile, Syrian state media reported that Turkish forces started shelling pro-government fighters entering Afrin.
Turkey's state-run Anadolu agency said that the pro-Syrian government forces withdrew after Turkish artillery units fired "warning shots" at the fighters.
Turkish President Recep Tayyip Erdogan said later that a convoy of a dozen vehicles carrying Shi'ite fighters was "forced to turn back" from the enclave following the shelling.
Turkish troops and Ankara-backed Syrian rebels have seized more than 40 villages since Ankara launched an air-and-ground offensive on Afrin on January 20, according to Syrian activists.
Turkey has vowed to clear the enclave of the YPG, which it considers a terrorist group, and warned Syrian pro-government forces against intervening in support of the Kurds.
Based on reporting by AP, Reuters, AFP, dpa, and the BBC