The massive military push to oust the so-called Islamic State from Mosul, Iraq's second largest city, involves Iraqis, Kurds, Americans and even members of the Iraq's Shi'ite community.
Iraqi special forces search a building located inside a church compound in Bartella, east of Mosul, Iraq on Oct. 21, 2016.
U.S. military officials have warned the operation, which is likely to include street battles once Iraqi and Kurdish troops fight their way inside Mosul, is likely to take weeks.
A family arrives in Qayyarah during an operation to attack Islamic State militants in Mosul, Iraq on Oct. 19, 2016.
The complexity of the fight became obvious after IS militants attacked Kirkuk, a city to the east of Mosul.
The fighting has also prompted a frenzied rush of civilians, who are fleeing IS-controlled Mosul by the tens of thousands at great personal risk to U.N. camps in Syria.