Delegations from Russia and Ukraine are in Istanbul, the Turkish capital, for the first face-to-face talks in more than two weeks hosted by the Turkish leader.
Ukraine says its top priority from the talks, which will begin today, is to negotiate a ceasefire.
But hopes of progress are slim, with both sides playing down the chances of a breakthrough.
In his welcome address, Turkish leader president Erdogan says it is time the talks yield “concrete results”.
Erdogan spoke of his “deep sorrow” that the conflict has entered its fifth week, saying turkey’s friendship with both countries gave it an obligation to mediate.
Turkey is a NATO member but retains strong ties with Russia. Mr. Erdogan has resisted joining the west’s sanctions against Moscow – one of the few countries still to do so.