Some 300 Russian military police have arrived in Syria to patrol the flashpoint Syrian-Turkish frontier, the Russian defence ministry said on Friday.
The military police, who arrived from the Russian region of Chechnya, will work to ensure the safety of the population and help Kurdish forces withdraw to a line 30 kilometres (18 miles) from the border, Moscow said.
More than 20 armoured vehicles were also sent to Syria to help carry out the tasks, the defence ministry said in a statement.
This week Russia and Turkey signed a deal that will see Russian military police and Syrian border guards “facilitate the removal” of Kurdish People's Protection Units (YPG) from within 30 kilometres of the border.
The Turkey-Russia agreement was reached after marathon talks between President Recep Tayyip Erdogan and President Vladimir Putin in the Black Sea resort of Sochi on Tuesday.
Russian military police conducted the first patrols on Wednesday.
The deal follows the decision by US President Donald Trump to pull US troops who were allied with Kurdish forces that bore the brunt of the fight against the militant Islamic State (IS) group in Syria.
But on Thursday the US said it would beef up its military presence to protect northeastern Syria oil fields as Kurdish forces abandoned several positions.