BEIRUT — President Trump’s surprise announcement Thursday that “we just took over” the last Islamic State-controlled territory in Syria came as news to U.S.-backed forces leading the fight on the ground, spokesmen said.

Fighters and civilians have streamed out of the Syrian hamlet of Baghouz in recent weeks, surrendering to U.S.-backed troops as the battle to rid the Islamic State group of its territory grinds to an end.

“You kept hearing it was 90 percent, 92 percent, the caliphate in Syria. Now it’s 100 percent we just took over,” Trump told U.S. troops during a refueling stop in Alaska on Thursday. “That means the area, the land, we have 100 percent, so that’s good.”

During a stop on his way back from Hanoi on Feb. 28, President Trump said “100 percent” of the territory held by the Islamic State had been retaken. (Reuters)

More than 5,000 miles away in Syria, however, members of the U.S.-backed ground forces said they were surprised. The “final decision” is yet to be made, said Adnan Afrin, a spokesman for the Syrian Democratic Forces (SDF).

“It’s not true, it’s not true, it’s not true,” said Rami Abdulrahman, director of the Syrian Observatory for Human Rights, the most prominent group monitoring Syria’s seven-year war.

And a spokesman for the YPG, a Kurdish militia that forms the majority of the U.S.-backed force, predicted that the fight would not end for at least a week.

“ISIS is not simply laying down arms and surrendering. Instead they’re preparing to make a last stand,” Zana Amedi wrote on Twitter.

It was unclear Thursday whether the president’s comments had been intended in general terms, or reflected a different understanding of the situation on the ground. Although a U.S.-led air campaign has rolled the Islamic State back from a territory the size of Britain to a sliver of less than a square mile, die-hard cadres are still pinned down in Baghouz, members of the U. S-backed SDF said.

The number of people inside the area has repeatedly confounded aid groups and military predictions in recent weeks. “We are told to expect more thousands to come out,” said Panos Moumtzis, the United Nations’ top humanitarian official for the Syrian crisis. At the displacement camp receiving Baghouz’s civilians, staff have been overwhelmed.

“It’s almost like having to build a city overnight for the thousands of people who keep newly arriving,” Moumtzis said.

Victory against the group there will mark a major milestone, robbing the militants of a proto-state that once straddled Syria and Iraq, challenging international borders and drawing foot soldiers from around the world. But with defeat looming, the group has switched gears. Experts warn that it is likely to emerge next as an insurgency, plaguing insecure pockets of Iraq and Syria and playing on long-standing divisions as it tries to recruit members afresh.

Trump announced in December that U.S. troops would be leaving Syria after achieving victory against the Islamist militants. In an apparent concession to fears that a rapid drawdown could leave a security vacuum in its wake, the White House announced this month that at least 400 troops will remain for the time being.