U.S.-backed forces ousted Islamic State from its last outpost in Syria, marking the end of a nearly five-year campaign that forced the extremist group to morph from a governing authority back into a guerrilla insurgency as swaths of territory were freed from its brutal rule.

The demise of the group’s self-proclaimed caliphate—which once covered an area the size of Portugal—comes as President Trump prepares to pull U.S. troops from Syria.

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