The Islamic State extremist group fired a munition at an Iraqi air force base that tested positive for mustard gas, the US Defence Department said Wednesday.
The Iraqi air base at Qayyarah West came under fire on Tuesday. An initial test of the munition, which the Pentagon says was either a rocket or a mortar round, returned a positive result "for a mustard agent."
The device was "imprecise and crude," a Pentagon spokesperson told dpa in an email.
No members of the coalition forces were injured in the attack, and none showed signs of mustard gas exposure. The personnel who conducted the tests underwent a routine decontamination process.
"This attack has not impacted our mission in any way, nor have we changed our security posture in the area around Qayyarah," the Pentagon statement said. "We train and equip ourselves and our partners for just this type of eventuality."