An Iraqi military spokesman says the long-awaited military operation to recapture the northern city of Mosul from Islamic State militants "has begun."

The spokesman for the Joint Military Command, Brig. Gen. Yahya Rasool, says Iraqi forces retook several villages on the outskirts of the town of Makhmour, east of Mosul, on Thursday morning.

Rasool says the U.S.-led international coalition is providing air support. He wouldn't divulge more details.

It was not immediately clear how long such a complex and taxing operation could take. Mosul lies 360 kilometers, or 225 miles, northwest of Baghdad.

It's Iraq's second-largest city and it fell to Islamic State group during the militants' June 2014 onslaught. Mosul is also the largest city in the Islamic State group's self-declared caliphate.