The U.S.-led coalition with Iraqi and Peshmerga forces has been preparing for months to begin the Mosul offensive. But ISIL too has been preparing. As forces advanced closer to Mosul, dark clouds appeared in the sky – the first signs of ISIL’s preparations.

Before the Mosul offensive was even launched – the battle began. As Peshmerga and Iraqi forces advanced towards frontlines near Mosul – blue skies turned into grey. ISIL set ablaze oil in trenches they had dug up around Mosul.

Photo taken on Oct. 17, 2016 shows the heavy smoke rising from oil wells which were destroyed by the Islamic State militants in Qayyarah, southern Mosul, Iraq. Iraqi Prime Minister Haider al-Abadi announced early Monday the beginning of a major offensive to retake the second largest Iraqi city of Mosul from the Islamic State (IS) group. (Xinhua/Liu Wanli)

The thick smoke created intense grey clouds – ISIL’s latest strategy to impair the visibility of coalition jets carrying out airstrikes against ISIL. The hazardous smoke has become visible in major cities such as Erbil. Citizens living in those areas have become concerned.

“It has a very bad impact on the region and the people of Erbil, because the smoke continuously spreads. It leads to bad health, and maybe people will get different kinds of disease from it,” said Shahin, an Iraqi citizen.

Environmental experts emphasize some groups of people may be more affected and that this was a serious problem.

“Smoke negatively impacts Erbil's people and the surroundings, especially for kids and pregnant women. The same goes for Kurdistan’s environment. It is expected that the effects will linger for some years, and so we need our allies and international organizations to do something to prevent these fires,” said Goran As’ad, Iraqi environmental expert.

This was not the first time ISIL was burning oil to cause damage before withdrawing from the Iraqi city of Qayarrah – the group had burned oil wells that poured onto the streets, creating black streams of oil.

ISIL is also known to plant IEDs, making their occupied territories dangerous to enter – yet as the Mosul offensive continues full force – with the cooperation of the U.S.-led coalition, Iraqi forces and Peshmergas, it seems, defeat is almost inevitable for ISIL.