Russia and Turkey have conducted joint air strikes against an Islamic State group's stronghold in northern Syria, according to the Russian military.
Lt Gen Sergei Rudskoi, of the military's General Staff, said nine Russian warplanes and eight Turkish jets had taken part in the strikes on the outskirts of al-Bab in the province of Aleppo.
Lt Gen Rudskoi's statement was the first acknowledgement of the Russian strikes in support of the Turkish offensive on al-Bab.
It highlighted an increasingly close alliance between Russia and Turkey, which last month jointly brokered a Syria truce and are working to prepare Syrian talks in Kazakhstan next week.
The two nations have backed opposing sides in the Syrian conflict, which has lasted nearly six years, with Moscow supporting Syrian president Bashar Assad and Ankara backing his foes.