ISIS is suspected of firing a shell with a mustard agent that landed at the Qayarrah air base in Iraq, where US and Iraqi troops are operating, according to several US officials.
No US troops were hurt in the incident on Tuesday or have displayed symptoms of exposure to mustard agent. One official said the agent had "low purity" and was "poorly weaponized." A second official called it "ineffective.
The substance is being sent to a lab.
----------------------------------------------
Get complete coverage of breaking news on CNN TV, CNN.com and CNN Mobile.
Watch CNN live or On Demand from your computer or mobile device using CNNgo.
----------------------------------------------
You have opted-in to receive this e-mail from CNN.com.
To unsubscribe from Breaking News e-mail alerts, go to: http://cnn.com/EMAIL/breakingnews/unsubscribe.html?l=domestic-adh-bn
One CNN Center Atlanta, GA 30303
(c) & (r) 2016 Cable News Network
