Turkish President Recep Tayyip Erdogan urged Syria on Wednesday to withdraw its troops from its military observation posts in northwestern Idlib province where clashes have intensified in recent days.
"At the moment, two of our 12 observation posts are behind the regime's lines. We hope the regime will withdraw from our observation posts before the end of the month of February," he told a meeting of his ruling party in Ankara.
"If the regime does not pull back, Turkey will be obliged to take matters into its own hands."
Eight Turkish troops and civilians were killed on Monday by regime fire in Idlib -- the last opposition bastion in the conflict-torn country.
Turkey killed at least 13 Syrian government troops in response, according to monitors, in the deadliest clashes since Ankara sent troops to Syria in 2016.
Erdogan has criticised Russia, a key backer of President Bashar al-Assad's regime, for failing to enforce peace agreements in the region and called for Moscow to "better understand our sensitivities in Syria".
"From now we will not turn a blind eye to any step that constitutes the violation of the agreements," he added.
Erdogan said this week's clashes amounted to a "new era" in Syria, and that any further attacks would be "responded to in kind".
"The air and ground elements of the Turkish armed forces will freely move in the Idlib region and if needed will launch an operation," he said.