Turkey warns Syria as army chief visits troops on border Turkey bombarded Syrian army positions again on Monday after a new shell strike on another border town. Troops loyal to the Assad administration are shelling our territory ... We are retaliating in kind. We are currently doing whatever the rules of engagement require us to do," said Erdogan, who has been one of the most vocal opponents of the regime of President Bashar al-Assad. He vowed to take any measure in the face of any Syrian threat to Turkish national security, saying: "The requirement of being a state means we must take any measure and be prepared for any possibility." Turkey has boosted its military defences on the volatile border over the past week, stationing tanks and anti-aircraft missiles there as well as troops. Last Wednesday's incident was the most serious between Damascus and Ankara since Syrian anti-aircraft fire brought down a Turkish fighter jet in June, and renewed fears that the Syrian civil war could erupt into a broader conflict.