US-backed forces encircling Raqqa expect the fight to oust the remnants of Islamic State from its most symbolic Syrian stronghold to take at least three months, despite rapid advances towards the city centre this week.
The coalition's advance met with fierce resistance on Wednesday, as fighters with Islamic State, also known as Isis, used an eighth-century fortified wall as a buffer against Kurdish and Arab fighters known as the Syrian Democratic Forces (SDF), while steadily closing in from its surrounds.
With the wall now breached, and Raqqa all but encircled, the fate of at least 60,000 residents trapped inside the city is growing increasingly uncertain.
A volunteer fighter with Kurdish troops said as many as 50 air strikes were hitting Raqqa each day, and observers suggested that as many as half of the reported 740 civilian deaths in Syria last month may have been caused by bombs dropped on the city by aircraft of the US-led coalition.
"We also see a lot of drone bombs," said Paul Hatfield, an American volunteer with Kurdish forces. "We had hundreds of them since we started in Raqqa."
Mr Hatfield said his unit was in a dense neighbourhood about 8km from the city centre, and had been holding the SDF’s western line of attack for the past two weeks. “It’s very dangerous, with a lot of [Isis] snipers,” he said.
The looming fall of Raqqa, the Syrian capital of its so-called caliphate, has squeezed Isis east from the city towards Deir ez-Zor and a 300km stretch of the Euphrates river valley near Iraq. Senior leaders have sought refuge in the town of Mayadin in this area.
The Euphrates river region is fast emerging as one of the most crucial parts of a country devastated by a multifaceted war, which international players are increasingly seeking to calm by carving out zones of influence across Syria.
Regional diplomats have earmarked at least five areas in Syria where neighbouring states could potentially help broker localised truces. But the complexity of the conflict and competing agendas have meant binding solutions remain elusive.
Syria’s future
Talks in Istanbul, Amman, London and Washington in recent weeks have attempted to find ways that the ultimate fall of Isis will not lead to a further conflagration, one that would turn what remains of Syria into an ungovernable rump.
Particular attention has been paid to southern Syria, where Russia has proposed to establish one of four "de-escalation" zones . The zone would cover the border town of Quneitra and the Golan Heights, where Israel believes Iran is attempting to consolidate a strategic hub.
One proposal put to Moscow is to allow Syrian rebel troops to return to the Jordanian border in return for Iran pulling its forces and proxies from the area. "It's a long shot," said an official in Istanbul. "But the Russians are keen to broker a deal. The peace process they started in Astana isn't working."
Moscow said it plans to send forces, most likely military police, to Syria within two or three weeks, after concluding a deal with Turkey and Iran.
Rex Tillerson, the US secretary of state, told his Russian counterpart, Sergei Lavrov, earlier this week that a solution for Syria was now "in Russia's hands". Mr Tillerson has since told senior European diplomats that his remarks were an attempt to "call Russia's bluff".
However, US allies in the region say Washington’s rapidly-declining interest in crafting any deal on ending the conflict suggests further US disengagement.
Eastern Syria, where Isis is preparing a last stand, is one of two areas of the country where the Trump administration retains an interest in the conflict – the other being the northeast, where 6,000 US-backed Kurdish and Arab troops are attacking Isis, diplomats said.
“It is becoming about Iran for them out there,” said one official. “It was about Isis and only Isis. But things are turning. How that works out is anyone’s guess. Though Iran are doing very well. They are patient, intelligent and cautious actors.
“The Americans have got nothing to counter them. One school of thought is just to leave it to them. But then, what will the Israelis do?”
Guardian service