US military vehicles are seen in the town of Bashiqa, east of Mosul, during an operation to attack ISIS militants in Mosul, Iraq, November 7, 2016.

:: US military advisors are operating inside the city of Raqqa, ISIS group’s last major bastion in Syria, a US official said Wednesday.

The troops, many of them special operations forces, are working in an “advise, assist and accompany” role to support local fighters from the Syrian Democratic Forces as they battle ISIS, said Colonel Ryan Dillon, a military spokesman.

The troops are not in a direct combat role but are calling in air strikes and are working closer to the fight than did US forces supporting the Iraqi military in Mosul.

“They are much more exposed to enemy contact than those in Iraq,” Dillon said.

He said the numbers of US forces in Raqqa were “not hundreds.”

The operation to capture Raqqa began in November and on June 6 the SDF entered the city.

With help from the US-led coalition, the SDF this month breeched an ancient wall by Raqqa’s Old City, where diehard militants are making a last stand.

Dillon said the coalition had seen ISIS increasingly using commercial drones that have been rigged with explosives. The militants employed a similar tactic in Mosul.

“Over the course over the last week or two, it has increased as we’ve continued to push in closer inside of Raqa city center,” he said.

The US military is secretive about exactly how big its footprint is in Syria, but has previously said about 500 special operations fighters are there to train and assist the SDF, an Arab-Kurdish alliance.