Turkey, a NATO member with the alliance’s second biggest army, scrambled two F-16 jets on Saturday after a Russian aircraft crossed into its airspace over its southern province of Hatay, the Turkish foreign ministry said.

The United States and its NATO allies denounced Russia for Saturday’s incursion, and Ankara threatened to respond if provoked again, raising the prospect of direct confrontation between the Cold War enemies.

NATO held an emergency meeting in Brussels of ambassadors from its 28 member states with secretary-general Jens Stoltenberg calling the incursions “unacceptable violations of Turkish airspace”.

NATO members “strongly protest” and “condemn” incursions into Turkish and NATO territory, the alliance said.

“Allies also note the extreme danger of such irresponsible behaviour. They call on the Russian Federation to cease and desist, and immediately explain these violations,” NATO said in a statement after the meeting.