US officials made it clear when Kurdish forces announced the start of their invasion of the ISIS capital city of Raqqa that their near-term goal was to surrounding the city. The appear to be amounting to surrounding a massive swathe of land, not just the city itself, with some 550 square kilometers marked out.
Kurdish officials say the effort is going according to plan, and that they have two different areas north of Raqqa which are effectively surrounded in the latest push from Ayn Issa. They remain far from the city of Raqqa, and there is no sign they are advancing to surround from any other directions.
That may prove hugely more difficult to the Kurdish SDF forces, for while “surrounding” the area north of Raqqa has just boiled down to advancing south from Ayn Issa, which they already control, the Kurds have no territory south of Raqqa, nor any holdings due east or west of the city.
In the past the Syrian military held the area south of Raqqa, though it has been contested on-again and off-again, and ISIS mostly holds this area. Similarly, ISIS controls most of the area to the east, and the western frontier is heavily contested between various rebel factions.