Sinjar, Iraq (CNN)Plumes of smoke blackened the sky above Sinjar as Kurdish forces, backed by intense coalition air support, tried Thursday to take back the northern Iraqi town from ISIS. <br /> <br />The operation includes up to 7,500 Peshmergas -- the Kurdish military force -- who are attacking the city from three sides to take control of supply routes, according to the Kurdish Region Security Council . <br /> <br />CNN senior international correspondent Nick Paton Walsh is with one of the three fronts of fighters who launched their liberation operation early Thursday morning against a backdrop of airstrikes. <br /> <br />"A pitch-black sky was lit up by a lot of coalition airstrikes following days of bombing. At dawn, a large procession of Peshmerga started snaking their way through Sinjar mountain and behind it," Paton Walsh said. <br /> <br />The coalition strikes were pounding the strategic city itself, he said, with four different columns of smoke darkening the horizon above: "The strikes on Sinjar almost make the sky over it look black. There's a vast amount of air power -- more intense than the fight for Kobani." <br /> <br />Liberation from ISIS comes at a cost <br /> <br />Liberation from ISIS comes at a cost 02:19 <br />Kobani is a Syrian border town that was wrested back from ISIS militants earlier this year after four months of fierce fighting that left parts of it entirely flattened. <br /> <br />Peshmerga and coalition unity <br />Reclaiming Sinjar is one big step toward dividing the "caliphate" that ISIS claims it is establishing across the region.
