In this photo taken on Wednesday, Feb. 17, 2016, soldiers from the Syrian army fire a rocket at ISIS group positions in the province of Raqqa, Syria.

Recent gains by US-backed fighters battling the Islamic State group in northeastern Syria are paving the way for an assault on Raqqa, the militants’ de facto Syrian capital, a US official said Wednesday.

A Kurdish-led alliance called the Syrian Democratic Forces (SDF) have encircled the town of Al-Shadadi in Hasakeh province in recent days. The fighters have enjoyed broad support from a US-led coalition conducting air strikes on ISIS targets.

“There’s still work to be done and we expect ISIL fighters to put up a fight, but we expect Shadadi to be liberated in the very near future,” Pentagon spokesman Captain Jeff Davis said, using an alternative acronym for the ISIS group.

Davis said the recapture of Al-Shadadi would be followed “in the very near future” by anti-ISIS forces encircling Raqqa, ahead of an assault on the city.

“The momentum is moving (to Raqqa), and the momentum currently is in Shadadi,” Davis said.

He declined to speculate on a timeline for a Raqqa push.

The Britain-based Syrian Observatory for Human Rights monitoring group said last week that the SDF were in control of al-Shadadi, but were still engaged in “mopping up” operations outside the town.

The United States has highlighted Raqqa, and the Iraqi city of Mosul, as key targets in the anti-ISIS fight.

ISIS forces seized Raqqa in early 2014 and declared it the capital of their so-called caliphate. In June the same year, the militants seized Mosul.

Rather than sending large deployments of US forces into Iraq and Syria to fight the ISIS group, the United States has focused on training and assisting local fighters, saying they are best able to sustain a lasting defeat of the jihadist group.

Since August 2014, the US-led coalition has pounded IS targets in Iraq and Syria. The militants have lost considerable ground in those two countries but expanded their presence in Libya.

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