(Bloomberg) -- Islamic State, the militant group that once controlled parts of Iraq and Syria, is completely eradicated from its last pocket of territory on the Euphrates River, the Syrian Democratic Forces announced on Saturday.

"Our forces have raised their flag over Baghuz and declare complete military victory over the terrorist Islamic State after six years of war," according to a statement on its website.

The predominantly Kurdish forces, backed by U.S.-led coalition support, began an offensive against IS in September to gain control of the area. Activists say some 470 civilians have been killed since the attacks started and many others have surrendered.

U.S. President Donald Trump in December said he would withdraw military forces from Syria, declaring Islamic State defeated. The announcement led to concerns that the U.S. was leaving Kurdish allies vulnerable to attacks from Turkey. Trump subsequently agreed to keep as many as 400 U.S. troops in the country after American military officials and members of Congress cautioned that a withdrawal was premature.

Islamic State had already lost almost all of the land it once held under its self-proclaimed caliphate. The group swept through Iraq and Syria in 2014, conquering large chunks of oil-rich territory before its major strongholds fell at the end of 2017. The U.S.-backed coalition, Iraqi and Syrian government forces, Syrian rebels, Russian airstrikes and Iranian-allied militias have all targeted the group.

Head of U.S. Central Command Joseph Votel, who’s stepping down this month, said the fight against Islamic State is far from over.

Islamic State has made a “calculated decision to preserve the safety of their families and preservation of their capabilities by taking their chances in camps for internally displaced persons, and going to ground in remote areas and waiting for the right time to resurge,” Votel told the House Armed Services Committee earlier this month.

To contact the reporters on this story: Dana Khraiche in Beirut at dkhraiche@bloomberg.net;Vivian Nereim in Riyadh at vnereim@bloomberg.net

To contact the editors responsible for this story: Alaa Shahine at asalha@bloomberg.net, Steve Geimann, James Amott

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