Turkey is asking allies including the United States to take part in a joint ground operation in Syria, as a Moscow-backed government advance nears its borders, raising the possibility of direct confrontation between the NATO member and Russia. A large-scale joint ground operation is still unlikely: Washington has ruled out a major offensive. But the request shows how swiftly a Russian-backed advance in recent weeks has transformed a conflict that has drawn in most regional and global powers.

The offensive, supported by Iranian-backed Shi’ite militias as well as Russian air strikes, has brought the Syrian army to within 25 km (15 miles) of Turkey’s frontier. Kurdish fighters regarded by Turkey as hostile insurgents have also exploited the collapse of positions held by other rebel groups to seize ground and extend their presence along the border. The advances have increased the risk of a military confrontation between Russia and Turkey. Turkish artillery returned fire into Syria for a fourth straight day on Tuesday, military sources said, targeting the Kurdish YPG militia which Ankara says is being backed by Moscow. READ MORE