What else?
BREAKING: Islamic State attacks US and Iraqi troops with MUSTARD GAS
VICTOR LASZLO
Although the CNN article claims that no one is displaying symptoms, this Wiki article explains that it takes 24 hours for symptoms of Mustard gas to show.
Washington (CNN)ISIS is suspected of firing a shell with mustard agent that landed at the Qayyara air base in Iraq Tuesday where US and Iraqi troops are operating, according to several US officials.
The shell was categorized by officials as either a rocket or artillery shell. After it landed on the base, just south of Mosul, US troops tested it and received an initial reading for a chemical agent they believe is mustard.No US troops were hurt or have displayed symptoms of exposure to mustard agent.