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
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Peshmerga forces advance in the east of Mosul to attack Islamic State militants in Mosul, Iraq, Oct. 17, 2016.
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Smoke rises from Islamic state positions after an airstrike by coalition forces in Mosul, Iraq, Oct. 17, 2016.
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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
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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.
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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.
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Peshmerga forces gather on the east of Mosul during preparations to attack Mosul, Iraq, Oct. 16, 2016.
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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.
The Battle for Mosul
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