US-backed Syrian armed groups have captured a number of villages in the first days of an offensive to retake the city of Raqqa from Islamic State militants, a war monitor and a Kurdish sources say.
The ground forces are being supported by air strikes mounted by a US-led coalition, the source said. But he predicted the battle to drive IS from their Raqqa, their main stronghold in Syria, would "not be easy".
The operation by the Syrian Democratic Forces (SDF), which includes the Syrian Kurdish YPG militia and some Arab groups, began on Saturday and aims to encircle and ultimately capture Raqqa. It should add to the pressure on IS as it faces a major assault on its Iraqi bastion of Mosul.
The attack, named "Euphrates Anger" so far appears focused on areas north of Raqqa, south of the town of Ain Issa, 50 km away.
The Syrian Observatory for Human Rights, an organisation that monitors the multi-sided Syrian conflict, said the SDF forces had so far captured a number of IS positions but there had been "no real progress".
The Kurdish source said a number of villages had been captured. IS had set off five car bombs as part of their defence, he said.
The SDF has been the main ally on the ground in Syria for the US-led coalition against Islamic State in Iraq and Syria, capturing swathes of northern Syria.
"The isolation of Raqqa, when complete, will liberate strategically valuable terrain surrounding Raqqa and enable the liberation of the city," Commander, Lt. Gen. Stephen Townsend said.
The operation will also cut off Islamic State militants from Mosul as Iraqi forces simultaneously try to take back that city, Townsend said.
Planning for the Raqqa assault has been complicated by factors including the concerns of neighbouring Turkey, which does not want to see any further expansion of Kurdish influence in northern Syria.
Additionally, Raqqa is a predominantly Arab city, and Syrian Kurdish officials have previously said it should be freed from IS by Syrian Arab groups, not the Kurdish YPG.
