The Battle for Mosul

Peshmerga forces advance in the east of Mosul to attack Islamic State militants in Mosul, Iraq, Oct. 17, 2016.

Smoke rises from Islamic state positions after an airstrike by coalition forces in Mosul, Iraq, Oct. 17, 2016.

This photo released on his official Facebook page shows Iraqi Prime Minister Haider al-Abadi, center, surrounded by top military and police officers as he announces the start of the operation to liberate the northern city of Mosul from Islamic State milit

Kurdish Peshmerga fighters stand on top of a military vehicle as they advance towards villages surrounding Mosul, in Khazer, about 30 kilometers (19 miles) east of Mosul, Iraq, Oct. 17, 2016.

Iraq's elite counterterrorism forces gather ahead of an operation to re-take the Islamic State-held City of Mosul, outside Erbil, Iraq, Oct. 15, 2016.

Peshmerga forces gather on the east of Mosul during preparations to attack Mosul, Iraq, Oct. 16, 2016.

Iraqi special forces soldiers deployed for an offensive to retake Mosul from Islamic State militants prepare to move out from a camp near Khazer, Iraq, Oct. 14, 2016.

Peshmerga fighters are seen in Khazer, west of Erbil, Iraq in this still frame taken from video, Oct. 17, 2016.

Smoke rises from clashes in the east of Mosul during clashes with Islamic State militants, Iraq, Oct. 17, 2016.