Syrian government forces have managed to recapture a strategic town in the north-western province of Idlib, four days after Turkey-backed rebels seized it.
The Britain-based Syrian Observatory for Human Rights said Syrian government forces backed by Russian warplanes managed to take full control of Saraqeb, after rebels regained it from them on Thursday.
Saraqeb is key to both government forces and rebels as it is located on a highway linking Damascus and the northern province of Aleppo.
It is the second-largest city after Maaret al-Numaan in Idlib, Syria's last opposition stronghold.
Syrian government forces and their allied militias had taken over Saraqeb earlier last month as part of a massive military campaign in the region.
On Sunday, Turkish Defence Minister Hulusi Akar said his country had launched a new military operation, called "Operation Spring Shield," against Syrian President Bashar al-Assad's forces, after a Syrian strike killed at least 34 Turkish soldiers on Thursday in Idlib.
Syria said on Sunday that it was closing the airspace in its flashpoint north-west, mainly Idlib.
The outbreak of violence has sparked fears of a new European migration crisis, after Ankara said its frontiers were open to those who wanted to head to Europe in light of last week's fatalities.
Thousands of migrants have been rushing to Turkey's borders with Greece and Bulgaria since then.
In response, the Greek army will carry out an exercise with live ammunition along the country's land border with Turkey on Monday, the Defence Ministry in Athens said.
The 24-hour drill will take place in the Evros region, used by migrants attempting to enter from Turkey. During the exercise, Greek authorities have banned the movement of civilians, vehicles and livestock in the zone.
Australian Associated Press