Turkey said Thursday that an airstrike by the Syrian government killed 29 of its soldiers in Idlib, a war-torn province in northwestern Syria that has become the site of an increasingly volatile military confrontation among Ankara, Damascus and Moscow.

The death toll was the highest for Turkish forces in a single day since Turkey began ramping up the deployment of troops to Idlib this month to block a Russian-backed Syrian military offensive.

Turkish President Recep Tayyip Erdogan convened an emergency meeting of his top security officials Thursday night, local media reported.

Fahrettin Altun, Erdogan’s spokesman, said Turkey would “retaliate against the illegal [Syrian] regime, which pointed their guns at our soldiers.”

Turkey has been trying to halt a rapid advance by the Syrian army across Idlib province and nearby areas, which have been held by rebels opposing the government of Syrian President Bashar al-Assad. The province is largely controlled by an extremist group that once was formally associated with al-Qaeda.

The Syrian offensive has sparked a massive humanitarian crisis and sent hundreds of thousands of displaced Syrians fleeing toward the Turkish border. Russia, which is the Syrian government’s principal ally, has carried out airstrikes to aid the Syrian advance and provided Assad’s forces with other military support.

Turkey has called for the restoration of a de-escalation agreement between Ankara and Moscow and threatened to take further military action if Syrian forces do not withdraw from areas they have captured in Idlib. But negotiations between Ankara and Moscow over the past month aimed at securing a cease-fire have faltered.

The Washington post