Islamic State militants may have fired a chemical rocket at American troops based in Iraq, the US military says.
A rocket that landed at Qayyarah air base near Mosul within several hundred yards of US troops may have contained mustard agent, it said.
No one was hurt in Tuesday’s attack on the base, which will be home to several hundred US soldiers.
It’d be the first chemical weapons assault on coalition forces in Iraq, if supported.
Troops stationed at the base are equipped to handle chemical attacks.
“On September 20, mid-afternoon Iraq time, the Iraqi air base at [Qayyarah] West came under attack by indirect fire,” the Pentagon said in a statement.
“An initial test of the remnants of the weapon used returned a positive test for a mustard agent. The device, likely a rocket or mortar, was imprecise and crude.”
Following decontamination, no service staff showed signs or symptoms of mustard exposure, the Pentagon said.
“This strike hasn’t affected our assignment in any way, nor have we changed our security posture in the region around [the base],” the statement added.
“We train and equip ourselves and our partners just for this type of eventuality.”
There was no immediate evidence of the attack in Baghdad, the BBC’s Middle East correspondent, Quentin Sommerville, reports.
However, there have been 20 documented instances of chemical weapons being used against Kurdish combatants in Iraq and a quarter of those instances involved mustard gas.
IS has been suspected of making and using petroleum chemical weapons in Syria and Iraq, where it additionally controls land.
Mustard agent in adequate quantities can maim or kill by damaging skin, eyes and airways.
Iraq’s second biggest city, Mosul, has been under IS management for the previous two years and the battle to retake it’s expected to start in the coming weeks.
US troops are providing support to local forces as they prepare for the offensive.