Pentagon welcomes advance by Islamic State-fighting allies in Syria

The Pentagon said the operation had pitted "well over a thousand friendly forces" against "several hundred enemies".

Washington: A coalition including Syrian Arab groups regained a swath of territory in northeastern Syria from Islamic State militants, a US military spokesman said on Wednesday, calling it an encouraging success.

The fighters, who are from the Syrian Democratic Forces (SDF) and its Syrian Arab Coalition subgroup, regained 87 square miles (255 square kilometers) near the town of al-Hawl, US military spokesman Colonel Steve Warren said.

The group "conducted an attack ... driving ISIL back," Warren said by videoconference from Baghdad, using an alternate acronym for IS.

"This is not a large tactical action," he said, but "we are encouraged by what we saw."

The spokesman said the operation had pitted "well over a thousand friendly forces" against "several hundred enemies" in the vicinity, after heavy US airstrikes had cleared the way.

Warren said the United States intended to "reinforce" the action, seeming to hint at further ammunition air drops to US-allied groups after those that took place last month.

The Syrian Democratic Forces were formed in mid-October as an alliance between the powerful Kurdish People's Protection Units (YPG) and other Syrian rebel groups.