President Vladimir Putin has ordered the partial withdrawal of Russian troops from Syria, during an unannounced visit there on Monday.
Russian military support has been crucial in turning the tide of Syria's civil war in Mr Assad's favour.
Mr Putin made a similar withdrawal announcement in March 2016, but Russian military operations continued.
"I order the defence minister and the chief of the general staff to start withdrawing the Russian group of troops to their permanent bases," Mr Putin said on Tuesday, according to the Russian RIA Novosti news agency.
"I have taken a decision: a significant part of the Russian troop contingent located in Syria is returning home to Russia," he added.
BBC News.