NATO says it has drawn up plans to protect Turkey should the war in Syria spill over its border again.
It comes as deadly fighting between Syrian rebels and government forces rages on. Around 90 people are believed to have been killed on Tuesday, according to the British-based Syrian Observatory for Human Rights.
In one of the latest clashes, rebels are reported to have taken control of the town of Maarat al-Numan, which lies on the main north-south highway in the northern province of Idlib.
Rebel suicide bombers are also thought to have struck an Air Force Intelligence base in Damascus.
But it remains unclear whether Syrian shells that have hit Turkish territory over the past week were aimed to strike there.
Turkey’s chief of general staff, General Necdet Ozel, flew to several bases to inspect troop readiness as Ankara keeps up its highly visible presence.