Ayn al-Arab: Russian military police began patrols on part of the Syrian border on Wednesday, quickly moving to implement an accord with Turkey that divides control of northeastern Syria.
The Kremlin told Kurdish fighters to pull back from the entire frontier or face being 'steamrolled' by Turkish forces.
Turkish President Recep Tayyip Erdogan echoed those warnings, saying his military would resume its offensive against Kurdish fighters if the new arrangements are not carried out.
Erdogan and Russian President Vladimir Putin reached an agreement on Tuesday that would transform the map of northeast Syria, installing their forces along the border and filling the void left by the abrupt withdrawal of American troops.
The Kurdish fighters, who once relied on the US forces as protection from Turkey, were given a deadline of next Tuesday evening to pull back from border areas they have not already left.
Kurdish forces completed withdrawing on Tuesday from a stretch of territory 120 kilometres (75 miles) wide along the border and 30 kilometres (19 miles) deep between the towns of Ras al-Ayn and Tal Abyad.
The new agreement with Russia allows Turkey to keep sole control over that area.
For the rest of the northeastern border, Russian and Syrian government forces will move in to ensure the Kurdish fighters leave.
Then after the deadline runs out on Tuesday, Turkish and Russian forces will jointly patrol a strip 10-kilometres (6 miles) deep along the border.
The Russian Defence Ministry said that a convoy of military police had crossed the Euphrates River and deployed in the Syrian border town of Kobane.
