It was the first sign of Sasha Troufanov since May, when the Palestinian Islamic Jihad militant group posted two videos of him. His family pressed for the release of all the hostages in Gaza.
Losing Syrian military bases would hurt the Kremlin’s attempts to project power in the Middle East and Africa.
Paramilitary forces ransacked villages and killed hundreds of people, activists said, hastening calls for the United Nations to deploy a mission to protect civilians.
The withdrawals by one of President Bashar al-Assad’s key backers come amid a resurgent rebel offensive.