Syria accused Ankara of “flagrant aggression” Sunday after Turkey shot down a warplane near the border, raising tensions as Syrian loyalists and rebels battled for control of a frontier crossing.

Turkey, which backs the uprising against President Bashar al-Assad, warned Damascus against testing its determination and pledged a tough response if Syrian warplanes violate its airspace again.

It was the most serious incident since Turkish warplanes last September downed a Syrian helicopter that Ankara said was two kilometres (more than a mile) inside its airspace. […]