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DEIR AL-ZOR PROVINCE, Syria — The Islamic State faced final territorial defeat on Saturday as the U.S.-backed Syrian force battling the jihadists said it was closing in on their last bastion near the Iraqi border, capping years-long efforts to roll back the group.

"We expect it to be over soon," Mustafa Bali, a spokesman for the Syrian Democratic Forces (SDF) told Reuters.

While the fall of Baghouz, an eastern Syrian village on the bank of the Euphrates River, would mark a milestone in the campaign against the jihadists, they remain a threat, using guerrilla tactics and holding some desolate land further west.

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An array of enemies, both local and international, confronted ISIS after it declared a modern-day "caliphate" in 2014 across large swathes of territory it had seized in Syria and neighboring Iraq.

Thousands of ISIS followers and fighters, who had retreated to Baghouz as the group was gradually driven out of those lands, have poured out of the tiny cluster of hamlets and farmlands in Deir al-Zor province over the last few weeks.

Their evacuation held up the final assault until Friday evening when the SDF said it had advanced and would not stop until the jihadists were defeated.

Several hundred people trickled out of the tiny cluster of hamlets and farmland through the day. The majority were women and children, who were searched in the open and separated from the men, who were taken for interrogation.

They bore various nationalities including Russian, Indonesian and Azerbaijani. One woman told Reuters that ISIS militants still inside Baghouz had dug in and were ready to fight to the death.

Bali said on Saturday that the SDF were advancing on two fronts using medium and heavy weaponry. Three SDF fighters had been wounded so far, he added.

The United States has about 2,000 troops in Syria, mainly to support the SDF in fighting against the Islamic State.

President Donald Trump announced in December that they would be withdrawn because "we have won against ISIS," a decision that shocked allies and top aides and prompted Defence Secretary Jim Mattis to quit.

Last month, the White House said around 200 U.S. troops would stay as "a small peacekeeping group" for a period of time.