A chemical attack by the Islamic State in Mosul over the weekend had no effect on U.S. forces or the Iraqi security forces who were targeted, a top general said Wednesday.

However, the military could not confirm reports that mustard agent was the chemical used by the group as it wages an increasingly vicious fight for the western section of the city, said Army Maj. Gen. Joseph Martin, commander of the Combined Joint Forces Land Component Command for the campaign in Iraq.