BEIRUT • Arab-Kurdish fighters backed by the United States yesterday cut the Islamic State in Iraq and Syria (ISIS) group's main supply route between Syria and Turkey in a major setback for the militants.
ISIS has come under growing pressure on various fronts in Syria and Iraq, where it established its self-declared "caliphate" in 2014.
The extremists lost control of a vital supply artery when Arab-Kurdish forces completely surrounded a key town held by them. "The Syrian Democratic Forces (SDF) cut off the last road from Manbij to the Turkish border," said the Syrian Observatory for Human Rights, a British-based monitoring group.
Manbij lies at the heart of the last stretch of territory along Turkey's border still under ISIS control, and was a key point on the militants' supply line from Turkey.
Other secondary roads to the frontier are more dangerous and difficult to access, Observatory head Rami Abdel Rahman said.
The US envoy to the anti-ISIS coalition backing the SDF, Mr Brett McGurk, confirmed the road had been severed. "ISIL terrorists now completely surrounded with no way out," he wrote on Twitter, using another acronym for ISIS.
This week, the SDF, backed by coalition air strikes, cut the road north out of Manbij to the ISIS-held border town of Jarabulus, which the militants had used as a transit point for fighters, money and weapons.
The SDF also blocked the road south out of Manbij heading to ISIS' de facto capital of Raqqa.
Thousands of residents have fled Manbij - held by ISIS since 2014 - but the militants who evacuated their families stayed to defend the town, the Observatory said.
About 20,000 people are still living in the town, which had a pre-war population of about 120,000 - mostly Arabs, but about a quarter Syrian Kurds.
Last month, the SDF launched attacks on two fronts from the north of Raqqa province towards Manbij and in the direction of the ISIS-held town of Tabqa on the same vital supply line further south.
Regime troops backed by Russian air strikes have also pushed an offensive to the south-west of Tabqa.
Russia and the US - despite backing different sides in Syria's conflict - have both focused efforts on fighting the militant group.
The five-year war has killed more than 280,000 people and displaced millions since it started in 2011 with the brutal repression of anti-government protests.
Late on Thursday, a food aid convoy entered the rebel-held town of Daraya near Damascus in the first such delivery since the start of a regime siege in 2012.