A U.S. diplomat said Thursday that the United States would remain engaged with Russia throughout 2018 in working to defeat Islamic State in Syria.

Brett McGurk, special presidential envoy for the Global Coalition to Defeat ISIS, told reporters the U.S. wants to settle the war in Syria through a constitutional process leading to U.N.-supervised elections.

"We'll also remain present in other areas of Syria to make sure that ISIS cannot return and to make sure that we can help with the stabilization efforts so people can return to their homes," McGurk said, using an acronym for the militant group.

Islamic State has lost 98 percent of its so-called caliphate in Syria, he said, citing U.S. efforts to de-escalate the fighting, as well as "really pragmatic, pretty hard-nosed diplomacy with the Russians."

He also said the U.N. had reported that 1,000 Syrian refugees have been returning home each month.

But nobody is "popping champagne corks" yet, McGurk said, stressing that IS was not "totally finished" in Syria and that there was still a lot of work to do.

VOA national security correspondent Jeff Seldin contributed to this report.