A thick column of black smoke hangs over the Iraqi Syrian border near the town of Ash Shaddadi in Syria ' s Hasakah province. Above the area are the circular contrails of coalition planes. Kurdish military sources on the Iraqi side of the border say ISIS strongholds and oil fields are being targeted south of Hasakah city. At the same time the new US-backed alliance in Syria, the Syrian Democratic Forces, has announced a new offensive has begun to liberate areas of Hasakah province occupied by ISIS. Coalition airstrikes and land offensives led by Kurdish forces on both sides of the border are aimed at interrupting ISIS supply lines, retaking territory the group has held for over a year and putting pressure on critical towns such as Deir Ezzor. Kurdish Peshmerga forces on the Iraqi side of the border - including a brigade of some 5,000 Yazidi fighters - are preparing for what officers describe as an imminent offensive to seize the town of Sinjar. There has been a sharp increase in airstrikes on ISIS-held parts of the town in the last few days. If ISIS loses Sinjar, it will be more difficult for it to resupply the city of Mosul, the largest it holds.