Syrian militias backed by the US-led coalition against Daesh cut the road between the militant-held city of Raqqa and Deir Al-Zor province in Syria on Monday, a Kurdish military source and the Syrian Observatory for Human Rights said. The advance by the US-backed Syrian Democratic Forces (SDF) means all land routes out of Raqqa are now cut, and the only remaining way out is south across the Euphrates River, the Kurdish military source said. "It is a big victory but there is still a lot to accomplish," the source said. The SDF includes the Kurdish YPG militia and allied Arab groups. The spokesman for the SDF could not immediately be reached for comment. The northern Syrian city of Manbij is under the protection of the US-led coalition against Daesh after an increase in "Turkish threats" against the city, a Kurdish-allied militia that controls the city said. Manbij has come into renewed focus since Turkey declared it the next target of the campaign it is waging with Syrian rebels in northern Syria to keep both Daesh and Kurdish fighters away from its border. The Manbij Military Council is part of the US-backed Syrian Democratic Forces (SDF), a militia alliance dominated by the Kurdish YPG group which is seen by Ankara as an extension of a Kurdish group that is waging an insurgency in Turkey. The Turkish government says the YPG remains in Manbij, though the YPG says it withdrew last year after the city was captured from Daesh in an SDF assault backed by the US-led coalition. In a statement released late on Sunday, the Manbij Military Council said the US-led coalition had increased its presence in Manbij and the surrounding countryside "after the increase in Turkish threats to occupy the city". "We in the Manbij Military Council confirm again that Manbij and its rural areas are under the protection of the Manbij Military Council and under the care of the international coalition and its protection," the Manbij Military Council said. After clashing with Turkey-backed Free Syrian Army rebels west of Manbij last week, the council declared a deal with Russia to hand villages at the frontline with Turkish forces to Syrian government control. Turkey views the YPG as an extension of the Kurdistan Workers' Party (PKK), which is waging an insurgency in Turkey.