US-backed Syrian fighters push back IS

US officials said thousands of fighters, supported by a small number of US special forces, were launching an offensive to capture the crucial swathe of northern Syria that militants have long used as a logistics base. The operation could take weeks.

The Syrian Observatory for Human Rights said the Kurdish YPG militia made up the majority of the fighters taking part in the assault by the Syria Democratic Forces (SDF) alliance, with the initial target of capturing the town of Manbij, contradicting US officials who said the bulk were Arabs. This is seen as important  to NATO member Turkey, which has opposed any further expansion of Syrian Kurdish sway at the frontier. The Syrian Kurdish YPG militia already controls an uninterrupted 400 km stretch of the border. An US official said Turkey supported the offensive. SDF and YPG officials could not immediately be reached for comment.

The Observatory said US-led air strikes in support of the ground operation killed 15 civilians including three children near Manbij in the last 24 hours. The Observatory’s reporting is based on an activist network in Syria. It said the SDF fighters had taken 16 villages and were at a distance of 15 km from Manbij.

Driving Islamic State from its last remaining foothold at the Turkish border has been a top priority of the US-led campaign against the group. The group controls around 80 km of the frontier stretching west from Jarablus.