According to the spokesman, the IS group's mustard gas is 'not generally in a lethal concentration' but more of an irritant
The Islamic State is likely to mustard gas as the Iraqi forces advance to re-take Mosul, IS group's last main stronghold in Iraq, a Pentagon spokeman said on Monday.
"We can fully expect that as this road towards Mosul progresses, ISIL is likely to try to use it again," Jeff Davis was quoted as saying by AFP.
Davis said that IS's ability to weaponise mustard agent has been rudimentary. Their mustard gas is typically a powder bound together with tar. The gas is more of an irritant than lethal, Davis said.
"It's not generally in a lethal concentration. It's more of an irritant than anything else, but again, not something we view as militarily significant," he said, noting that the gas form of mustard agent used in the First World War was far more lethal, Reuters reported.
"We recognise this is real. They're dead set on it. They would love to be able to use chemical weapons against us, against the Iraqis as they move forward. We are making every effort to make sure that we're ready for it."
Davis added that Iraqi soldiers have been given training and have practiced to be in a situation of exposure to the IS chemical weapon. The United states has provided more than 50,000 gas masks to the Iraqi forces, he said.
"We want to make sure that the Iraqi security forces and the Peshmergas (Kurdish fighters) have the ability to detect this and to defend against it," Davis said.
A rocket was launched, with a possible chemical agent, against US soldiers at a base near Qayyarah, a northern town in Iraq. The Pentagon suspects that the IS group used mustard gas in the attack last week.
Hundreds of US troops are working to prepare an airfield for an Iraqi offensive to recapture the city of Mosul neat the base, Reuters reported.
Iraqi security forces, backed by US-led coalition air power, are in the final weeks of preparing operations ahead of an assault to recapture Mosul, according to AFP.
(WION with inputs from agencies)