Supported by U.S.-led airstrikes, Kurdish Iraqi troops on Thursday seized part of a highway that is used as a vital supply line by the Islamic State group, a key initial step in a major offensive to retake the strategic town of Sinjar from the militants.

The town was overrun by the extremists as they rampaged across Iraq in August 2014, leading to the killing, enslavement and flight of thousands of people from the minority Yazidi community. The U.S. later launched an air campaign against the Islamic State militants, also known as ISIL, ISIS and, in Arabic, as Daesh.

Hours into Thursday’s operation, the Kurdish Regional Security Council said its forces controlled a section of Highway 47, which passes by Sinjar and indirectly links the militants’ two biggest strongholds — Raqqa in Syria and Mosul in northern Iraq — as a route for goods, weapons and fighters. […]