The Kurds will have to make concessions. The agreement asks the YPG or SDF — an American-backed fighting force made up largely of the YPG — to make concessions outside of the current area of conflict. The YPG in the agreement are meant to withdraw from the towns of Manbij and Tal Rifaat.

The deal also implies that the Kurds have a new guarantor. After President Trump effectively abandoned the Kurds, by ordering the sudden withdrawal of US forces from Syria and leaving the YPG exposed to a Turkish advance, that role now falls to the Russians.

Now Moscow will have to deploy more troops and equipment to Syria as part of an expanded mission. But the question remains open: With so few Russian forces on the ground, Syrian Kurds may have little alternative but to allow Syria's Russian-backed military into Kurdish-held areas.