Turkey scrambled fighter jets on Wednesday as a Syrian warplane bombed the town of Ras al-Ain near the Turkish border for a third day as forces loyal to President Bashar al-Assad pressed an air assault to dislodge opposition fighters.
The jet struck twice before circling and bombing again, rocking buildings on the Turkish side of the frontier and sending up huge plumes of smoke, a Reuters reporter in the Turkish border town of Ceylanpınar said.
It marked the third day of a jet bombardment that has brought Syria's civil war back perilously close to Turkish soil, testing a promise by Ankara to defend itself against any spillover of violence from its neighbor.
Turkey has scrambled jets close to its southeastern border before in response to Syrian aircraft approaching Turkish airspace as they carry out operations against Syrian rebels.
The reporters, on the Turkish side of the border, could not see the jets but heard them approach from Turkish territory shortly after a Syrian warplane struck Ras al-Ain for a third day.
Turkey's defense minister, İsmet Yılmaz, indicated that Turkey would use military force in response to any incursions by Syrian aircraft. Last month, Turkish artillery fired on targets in Syria after Syrian shells landed inside Turkey and killed several Turkish civilians in one instance.
"The necessary response will be given to Syrian planes and helicopters that violate our border," Yılmaz said.
At least three villages along Turkey's border with Syria have been evacuated to protect villagers from any spillover of fighting between Syrian government forces and opposition fighters.
State-run Anatolia news agency and other Turkish media say several villages west of Ceylanpınar have been evacuated because of concerns about the fighting on the other side of the border.
Rebels overran Ras al-Ain last week during an advance into Syria's mixed Arab and Kurdish northeast that has triggered some of the biggest refugee movements of the conflict.
Some 140 km (90 miles) to the west, three Turkish border villages were evacuated on Tuesday, a security official told Reuters, citing "security reasons".
Turkish media reports said the villages, located in the Suruç district of Şanlıurfa province, had a combined population of around 1,000. The official declined to elaborate, but the move suggested the border clashes could be spreading.