The long-anticipated campaign to reclaim Mosul from the Islamic State began Monday. It is the largest military operation in Iraq since U.S. forces left five years ago.
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.