Turkey has shot down a Syrian warplane during pitched fighting between Syrian rebels and government troops near the border.
Turkish Prime Minister Recep Tayyip Erdogan says the Syrian plane violated Turkish airspace. Syrian state TV says the plane was pursuing rebels in Syrian territory.
A Syrian military source said the pilot was able to eject. A military spokesman described Turkey's action as "blatant aggression."
Erdogan warned Syria the "response will be heavy" if it violates Turkey's airspace.
Syrian rebels and government forces have been fighting for control of the Kasab border crossing in Syria's Latakia province for three days.
Meanwhile, political tensions sparked by the Syrian civil war continue to spill over in neighboring Lebanon. Supporters and opponents of Syria's President Bashar al-Assad fought in a Beirut neighborhood overnight. At least one person died in the gunbattle.