Russia and Turkey carried out their first joint airstrikes against Islamic State positions in Syria on Wednesday, further expanding their budding military cooperation, the Russian military said.

Russia and Turkey back opposing sides in Syria’s five-year civil war.

But now, the Russian Air Force has gone a step further by collaborating on missions with Turkey’s Air Force, the Russian military announced.

It is unusual, to say the least, for the Russian air force to conduct joint air strikes alongside a Nato member like Turkey.

Four Su-24s, four Su-25s and one Su-34 on the Russian side, and four F-16s and four F-4s on the Turkish side participated in the operation and 36 targets that had been selected in advance by military officers from the two countries were hit.

“Turkey is going to be an increasingly unreliable ally” said Eric Edelman, a former American ambassador to Turkey. “It is a worrisome development and underscores the need for a very high-level strategic dialogue with Turkey that is long overdue”.