MANBIJ, Syria (AP) — Even as President Donald Trump mulls a U.S. pullout from Syria, insisting that the Islamic State group is "almost completely defeated," the extremist group is showing signs of a revival.

Despite being kicked out of the main towns they once occupied near the Iraqi border, the militants have regrouped elsewhere and revised their tactics, recently mounting a brazen attack on a border city in eastern Syria and expanding their footprint inside the Syrian capital itself.

Talk of a U.S. troop withdrawal has alarmed the United States' main ally in Syria, the Kurds, who fought alon...