WASHINGTON — Even as President Donald Trump reluctantly signed new Russia sanctions into law this month, US officials expressed growing confidence that cooperation with Moscow on a Syria cease-fire is working. They believe the success of a deal in southwest Syria, negotiated by the United States, Russia and Jordan and announced last month, could prove a model for broader US-Russia cooperation on an interim stabilization plan after the defeat of the Islamic State (IS).

“Despite all of our tensions with Russia, we also look for areas where we have to find a way to work together, and I think Syria exemplifies that,” Brett McGurk, the US envoy in the coalition to defeat IS, told journalists at the State Department last week.

As the US-backed Syrian Democratic Forces (SDF) have ramped up their campaign to take the IS stronghold of Raqqa, US negotiations with Russia have produced agreement on “deconfliction” maps delineating the location of forces aligned with Russia and the United States so they do not come into conflict, McGurk said.

One such boundary near Tabqa, south of Raqqa, “has held extremely well,” McGurk said. “This is now in place. Our military personnel speak with the Russians every day, and we, of course, have diplomatic consultations on issues like this far less frequently but whenever we need to.”