Columns of Iraqi and Kurdish forces backed by US-led airstrikes slowly advanced on Mosul from several directions on Monday, launching a long-awaited operation to retake Iraq's second largest city from ISIS group.
As airstrikes sent plumes of smoke into the air and heavy artillery rounds rumbled, troops pushed into abandoned farming villages on the flat plains outside the city. But they were slowed by roadside bombs and by suicide car and truck bombs hurled at them by the militants.
The unprecedented operation is expected to take weeks, even months. Though some of the forces are less than 30km (20 miles) from Mosul's edges, it was not clear how long it will take to reach the city itself. Once there, they have to fight their way into an urban environment where more than one million people still live.
