Government forces have retaken control of a strategically important town in southern Syria, activists say.
Sheikh Miskeen, which lies on one of the main routes from Damascus to the city of Deraa and the Jordanian border, fell after a month-long battle.
Russian warplanes were reported to have played a key role in the offensive.
Russia's foreign minister meanwhile declared its intervention had changed the course of the conflict in Syria, ahead of the start of peace talks.
Sergei Lavrov also warned it would be impossible to negotiate a political settlement without allowing Kurdish groups to attend.
The UN has invited Syria's government and opposition to indirect "proximity talks" that are due to start in Geneva on Friday, but a statement released on Tuesday did not give any details as to who had been invited or how many groups may take part.
There was a delay in sending out the invitations because of disagreements over who should be included in the opposition delegation.