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FILE - In this Aug. 31, 2016 file photo, Iraqi firefighters battle large fire at oil wells as they trying to prevent the flames from reaching the residential neighborhoods in Qayara, Iraq. A fire at one of Iraq’s major oil fields could hinder military and humanitarian efforts as operations to recapture the Islamic State stronghold of Mosul get under way. Black smoke continues to billow into the air from the Qayara oil field, damaged by IS militants last month as they fled the town. There are slow-going Iraqi efforts to contain the fires, but smoke and toxic fumes continue to pollute the air in the area. (AP Photo, File)

FILE - In this Aug. 31, 2016 file photo, Iraqi firefighters battle large fire at oil wells as they trying to prevent the flames from reaching the residential neighborhoods in Qayara, Iraq. A fire at one of Iraq’s major oil fields could hinder military and humanitarian efforts as operations to recapture the Islamic State stronghold of Mosul get under way. Black smoke continues to billow into the air from the Qayara oil field, damaged by IS militants last month as they fled the town. There are slow-going Iraqi efforts to contain the fires, but smoke and toxic fumes continue to pollute the air in the area. (AP Photo, File)

Iraq War

President Obama announced on Oct. 21 that the United States is pulling all its troop from Iraq by the end of the year. (ABC News)