Story highlights The US led coalition has begun planning for an internal security force of local recruits that could "hold" Raqqa once military operations are over

About 20 percent of the city has been taken back by SDF fighters

(CNN) US backed Syrian Democratic Forces (SDF) pushing into Raqqa on two fronts are now less than three miles apart from each other, but it could still be weeks if not months before they are able to fully liberate ISIS's once self-declared capital, according to a US defense official directly familiar with the status of the fight.

Nonetheless, the US-led coalition has begun planning for an internal security force of local recruits that could "hold" Raqqa once military operations are over.

As of now only about 20 percent of the city has been taken back by SDF fighters, the official said. Shortly after entering the city area several days ago, the SDF encountered significant ISIS opposition and since then there has "not been considerable progress," the official said.

These SDF forces are pushing in from both the west and east, the official said. Additional SDF forces are attempting to move in from the north. While the overall 55,000-man SDF force is made up of about half Arab and half Kurdish forces, the units operating in and around Raqqa are 80 percent Arab, in keeping up with the ethnic makeup of the area.

Progress has been made in the northeastern sector of the old city area. After SDF breached the old city wall they were able to move about 1,500 feet past the wall into two foothold areas in the old city. US officials have said it's not clear at this point how many civilians or ISIS fighters are still inside Raqqa but overhead imagery has confirmed ISIS has laid booby traps and improvised explosive devices (IEDs) as it has done in other areas.

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