"We will first undertake an effort to isolate Raqa to set the stage for an eventual assault on the city itself to liberate it" from IS control, a US official told AFP on condition of anonymity, as a US-backed Kurdish-Arab alliance launched an offensive on the city.
The official said the Syrian Democratic Forces (SDF) "is the partner force most capable of acting soon to isolate Raqa, and we believe the inclusion of fighters from the local population is an important advantage the SDF brings to this effort.
The US official compared the Raqa operation with the meticulous, multi-step plans to retake the IS-occupied northern Iraqi city of Mosul.
"We are working to further pressure ISIL in Raqa concurrent with significant operations under way in Iraq," the official added, giving no further details.