Turkey has sent new military reinforcements including troops, vehicles and equipment into northern Syria, a war monitoring group and rebel and Kurdish sources said on Wednesday.
The British-based Syrian Observatory for Human Rights said the forces had crossed the border in the last 24 hours and headed towards areas south of Azaz town, which is held by Turkish-backed Syrian rebels.
To Azaz’s south are areas controlled by the Kurdish YPG militia, which Turkey has fought in northern Syria.
The Observatory said the reinforcements were part of preparations for new joint attacks on the YPG by Turkish forces and their Syrian rebel allies in that area of Syria's northwest. The area is separated from the main territory the YPG and its allies control in the northeast.
A rebel from a Turkish-backed group confirmed Ankara had sent more forces.
“Turkish forces are now inside Syria ... the forces are huger reinforcements that have been entering since last night,” said Mustafa Sejari of the Liwa al-Mutasem group.
Turkish opposition to what it says is Kurdish encroachment along its long border with Syria has complicated US strategy in the region, because Washington supports the YPG and its allies in the fight against ISIS.
The YPG is a key part of the Syrian Democratic Forces (SDF), which a US-led coalition is supporting with air strikes and military advisers on the ground to fight ISIS in its stronghold Raqqa.
Turkey launched an offensive in northern Syria in August last year, sending tanks and warplanes across the border to support Syrian rebels fighting both ISIS and the YPG.
It helped them carve out a big portion of northern Syria, helping ensure the YPG and its allies could not link the 400-km (250-mile) stretch of territory they hold in the north and northeast with the pocket they hold west of Azaz.
The YPG is linked to the PKK, a Kurdish group fighting an insurgency in Turkey’s southeast.
Turkey sends military reinforcements into northern Syria