The battle for Mosul: 5 key things to know

Kurdish peshmerga fighters, who are allied with the Iraqi army, stand atop military vehicles on Monday as they advance toward villages about 20 miles east of Mosul.The Iraqi military said an operation to retake Mosul from the Islamic State was launched before dawn on Monday.
Kurdish peshmerga fighters, who are allied with the Iraqi army, stand atop military vehicles on Monday as they advance toward villages about 20 miles east of Mosul.The Iraqi military said an operation to retake Mosul from the Islamic State was launched before dawn on Monday.