The US-backed Syrian Democratic Forces (SDF) started an attack to capture Daesh’s last remaining shred of territory in eastern Syria on Sunday and were exchanging fire with the jihadist militants, an SDF official said.

“The military operations have started. Our forces are now clashing with the terrorists and the attack started,” Mustafa Bali, head of the SDF media office, told Reuters.

The United States is “very optimistic” that France and Britain will participate in a residual force that US President Donald Trump wants to leave in Syria, his national security advisor said Sunday.

 “Certainly in conversations this past week with my British and French counterparts, I’m very optimistic that they’re going to participate,” John Bolton said, in an interview with ABC’s “This Week.”

 “It hasn’t happened formally yet, but they’re looking at it,” he said, adding that the chairman of the Joint Chiefs of Staff, Joe Dunford, is working to set up the force.

 Bolton insisted there was no contradiction between Trump’s assertion that the caliphate declared by the Daesh group has been eliminated 100 per cent, and the assessment of the top US commander in the Middle East, who told Congress last week the fight is “far from over.”

 “The president has been, I think, as clear as clear can be when he talks about the defeat of the Daesh territorial caliphate,” Bolton said.

 “He has never said that the elimination of the territorial caliphate means the end of Daesh in total. We know that’s not the case.”

 “But one reason that the president has committed to keeping an American presence in Iraq and a small part of an observer force in Syria is against the possibility that there would be a real resurgence of Daesh, and we would then have the ability to deal with that if that arose.”

 Trump abruptly announced in December the immediate and complete withdrawal of the 2,000 US troops deployed in northeastern Syria.

 Then, under pressure from Congress and the Pentagon, he agreed to leave a residual force of some 200 US troops, which he wants to be reinforced by allies in the anti-Daesh coalition.

 An objective of the international force is to guarantee the security of its Syrian Kurd allies. Turkey, a NATO member, views the Kurdish combatants as terrorists, and the Europeans fear they would be vulnerable if Ankara launched an offensive.

The Kurdish-led fighters pushed into the ragged tent encampment some 10 days ago as they and their US-led coalition backers pounded the Daesh, but they soon paused to allow more civilians to leave.

The no-man’s land between the SDF and the Daesh is filled with abandoned cars, shreds of clothing and holes dug by Daesh fighters and civilians for shelter.

The charred and twisted remains of a truck’s freight trailer lie on the ground.

Once a Daesh ammunition cache, it was hit during the most recent spurt of fighting, sending a pillar of black smoke jutting into the sky for days.

“When the sun comes up, civilians come towards us... but (Daesh) snipers fire on them to force them back,” Ahmad al-Siyyan, a fighter with the Syrian Democratic Forces, said.

A fragile ceasefire has held since the last round of fighting, as the SDF continues its push to clear the redoubt of non-combatants.

“We’ve managed to pull some civilians out of the camp,” he added.

The US-backed fighters have been hoping for weeks that the final day has come for Daesh’s “caliphate”.

Tens of thousands of women, children, and men have streamed out of the besieged bastion since December. Thousands more poured out after last week’s fighting, upending assumptions that few families remained holed up in the area.

Black smoke billows into the air from Daesh-held area of the camp where SDF fighters say extremists sometimes burn tyres.

Sporadic bursts of gunfire echo across the flat dusty terrain, punctuated by a singular roaring explosion.

The ground floor of the pockmarked building serving as the SDF front line position is strewn with syringes and packs of medicine -- remnants of a Daesh field hospital.

Spent ammunition of all sizes lie between zig-zagging trenches, scorched pots and pans and scraps of clothes left behind.

Agence France-Presse