CEYLANPINAR, Turkey Turkey scrambled fighter jets to its southeastern border with Syria on Wednesday in response to a renewed Syrian air assault of the rebel-held frontier town of Ras al-Ain, Reuters witnesses said.
Syrian President Bashar al-Assad's air force has been bombing Ras al-Ain for days, trying to dislodge anti-Assad rebels who overran the town last week during an advance into Syria's mixed Arab and Kurdish northeast.
A Reuters reporting crew on the border heard warplanes inside Turkish territory shortly after a Syrian jet bombed Ras al-Ain, which abuts the Turkish settlement of Ceylanpinar.
Turkey has sent jets before to its 900 km (560 miles) border with Syria and has responded in kind to stray Syrian shelling, but there was no immediate official confirmation from Ankara that it had scrambled fighter planes on Wednesday.
A Syrian warplane roared along the frontier and struck twice before circling and bombing again, rocking buildings in Ceylanpinar and sending up huge plumes of smoke over Ras al-Ain. There was no word on casualties.
A trickle of refugees clambered with the belongings through the flimsy barbed-wire fence between Ras al-Ain and Ceylanpinar, which were only divided from each other when new borders were drawn after the Ottoman empire collapsed in World War One.
The assault has brought the war back perilously close to Turkish soil, testing a promise by Ankara to defend its border.
It has also led to some of the biggest refugee movements of the war. More than 120,000 Syrian refugees are sheltering in camps in southeastern Turkey, a region where Ankara is also fighting an emboldened Kurdish insurgency.
Turkish Prime Minister Tayyip Erdogan, one of Assad's fiercest critics, said on Tuesday his government would not refrain from a "harsher response" on the border.
He chaired a meeting with Turkey's foreign minister, defense minister and the military's chief of general staff on Tuesday but no details of their talks have emerged.
Turkey's calls for a buffer zone inside Syria have so far gained little traction among Western powers.
Ankara is now talking to its NATO allies about the possible deployment of Patriot surface-to-air missiles to the border in what could be a potential prelude to enforcing a no-fly zone.
West of Ceylanpinar, a Turkish security official, who declined to be named, said three Turkish border villages had been evacuated on Tuesday, citing "security reasons".
Turkish media reports said the villages, located in the Suruc district of Sanliurfa province some 140 km (90 miles) west of Ceylanpinar, had a combined population of around 1,000.
Suruc lies across the border from the Syrian town of Kobani, which Syria's Kurdish Democratic Union Party (PYD) said in August was under its control.
Turkey says the PYD is linked to the outlawed Kurdistan Workers Party (PKK), which took up arms in 1984 and is fighting for autonomy in the southeast.
Ankara has accused Syria of arming the PKK, designated a terrorist group by the United States, European Union and Turkey.