The Syria Democratic Forces said on Sunday it would soon launch an operation to take back Raqqa, the Syrian city that has acted as the capital for ISIS. The coalition, which is backed by the U.S., is made up of the Kurdish YPG unit and ethnic Arab militias. The SDF has made significant progress on the ground in Syria against ISIS in recent years. Turkey, which neighbors Syria, considers the YPG to be a terror organization, and is therefore not supporting the operation. Coalition forces hope to prevent militants escaping from Mosul—where a counter-ISIS military offensive was recently launched—into Syria, in particular Raqqa.