ANKARA

One Turkish soldier was martyred and three others injured Thursday when their observation post in Syria’s Idlib province came under shelling and mortar fire. 

In a statement, the Turkish National Defense Ministry said Syrian regime forces carried out the attack on the post in the province’s de-escalation zone. 

The wounded were evacuated and have begun receiving medical treatment, the ministry said.

Russia's Ankara attache was summoned to military headquarters and was told that the attacks will be "responded in the strongest way," the ministry noted.

The ministry tweeted on Friday that regime positions which carried out the attack were targeted successfully.

Turkey and Russia agreed last September to turn Idlib into a de-escalation zone in which acts of aggression would be expressly prohibited.

The regime, however, has consistently broken the terms of the ceasefire, launching frequent attacks inside the de-escalation zone.