The presidents of Russia, Turkey and Iran will meet on Wednesday for the first in a series of summits aimed at re-booting the peace process in Syria with the regime forces gaining an upper hand over rebels and Daesh.
Russian leader Vladimir Putin will host Turkey's Recep Tayyip Erdogan and Iran's Hassan Rouhani in the Black Sea resort of Sochi ahead of parallel UN-led talks in Geneva set for November 28.
The meeting - the first such three-way summit between the trio - comes as Ankara, Moscow and Tehran cooperate with increasing intensity on ending the over six-year civil war in Syria that has left hundreds of thousands dead and millions homeless.
The three countries have backed negotiations in the Kazakh capital Astana that have brought together the representatives of the opposition and the regime seven times this year.
The talks have led the creation of four so-called "de-escalation zones" that have produced a drop in violence, but sporadic fighting and bombardment has continued.
Moscow is now seeking to steer the process, which has so far focused on military questions, in a political direction.