The U.S.-backed Syrian Democratic Forces have taken control of 80 percent of the city of Manbij and ousted all but a handful of Islamic State fighters, BBC reported Aug. 6. The Islamic State militants remaining have been using civilians as human shields, making continued progress against them difficult. The Syrian Democratic Forces consist of Sunni Arab, Kurdish and Assyrian Christian militias backed by U.S.-led coalition airstrikes. These militias launched an offensive across the Euphrates River two months ago aimed at taking key territory from the Islamic State, surrounding Manbij itself entirely in June. The area west of Manbij is one of the most highly populated regions in the self-declared caliphate. And because it borders Turkey, it serves as a transit point for smuggled supplies, weapons and foreign fighters — the last significant one the Islamic State has left.