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.
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.
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.
The Battle for Mosul
The Battle for Mosul
