Turkey struck Syrian military targets in response to a mortar shell fired from Syria landing on the Turkish side of the border, the Anatolia news agency reported on Friday.
The mortar shell exploded about 1 kilometre from a Turkish military base, in a wooded area in the southern province of Hatay, dpa reported.
Relations between the two neighbours have deteriorated since the regime of Bashar al-Assad started cracking down on its opponents in March 2011.
The United States, Germany and the Netherlands have sent Turkey Patriot missile batteries to help their NATO ally defend its border, where rockets from Syria have hit civilian areas.