Scorched earth and blackened skies cover this Iraqi oil field.

Engineers at the Allas Oil Field are trying to extinguish oil field fires set by the Islamic State. They were ignited to impede airstrikes, using rising smoke to block pilots’ views. The oil field, located south of Hawija, had been a major ISIS revenue source. When Iraqi forces launched an offensive in September, ISIS lit the wells on its way out.

Well fires have been strategically set before. In 1991, Saddam Hussein blew hundreds of Kuwait’s wells, which took months to extinguish.

Military officials say the fires in Iraq will take a few days to be put out.