US-backed forces fighting Islamic State enter Syria stronghold of Raqqa

Kurdish and Arab forces backed by the US have entered Islamic State’s de facto capital of Raqqa, setting the stage for what could be a months-long campaign to reclaim the militants’ largest stronghold in Syria.

Raqqa has served as an important ISIS hub to recruit, inspire, finance and plan external attacks, according to Ryan S. Dillon, spokesman for Combined Joint Task Force-Operation Inherent Resolve.

The Syrian Democratic Forces (SDF), a coalition of Kurdish and Arab fighters, breached the outer city limits of Raqqa, seizing a 1,000-year-old fortress in the west and a neighbourhood on the eastern side of the city, two days after announcing the start of the offensive.

“Raqqa to them is the capital of the caliphate, and they [ISIS] have fortified it to a great extent,” Nouri Mahmoud, a spokesman for the People’s Protection Units (YPG), the Kurdish militia taking part in the assault, told the Guardian newspaper.

"As expected, the tight confines of the remaining neighborhoods, the well-defended urban canyons, have proven to be very difficult to liberate," Dillon told Pentagon reporters.

The operation – codenamed Operation Wrath of Euphrates – to reclaim Raqqa is led by the SDF, whose largest component is the YPG, and is backed by US air power.

If successful, it would deprive ISIS of its second largest city, with a simultaneous campaign to take back Mosul in Iraq also under way.

It would be a major blow to the militant group’s efforts to take advantage of chaos in Iraq and Syria, three years after it declared a caliphate across the borders of both nations.

But forces on the ground face major challenges in their advance, including what Mahmoud described as an effort by ISIS to use civilians to slow down the SDF’s advance, numerous mines both outside and inside the city, booby traps, vehicles wired with bombs, a network of tunnels under the city, and suicide bombers.

“They are taking all sorts of measures because they know losing Raqqa is the beginning of the end for Daesh,” he said, using another common name for the group. “So in any areas they see advances, they are using the civilians.”

According to Dillon, ISIS has reverted to brutalising and murdering civilians. He noted that the United Nations reported on 6 June that 163 bodies of murdered Iraqi men, women and children lay on the streets of the Sheer neighbourhood in western Mosul after being shot and killed by ISIS snipers when they desperately tried to flee to safety.