The development, which investigators said involved toxic industrial or agricultural chemicals fired in Iraq and Syria, signaled a potential escalation of the group’s capabilities.
The Islamic State group appears to have manufactured rudimentary chemical-warfare shells and attacked Kurdish positions in Iraq and Syria in recent weeks, according to field investigators, Kurdish officials and a Western ordnance-disposal technician who recovered one of the shells.
The development signaled a potential escalation of the group’s capabilities, though it was not without precedent.
Sunni militants in Iraq have occasionally used chlorine or old chemical-warfare shells in makeshift bombs against U.S. and Iraqi government forces. Kurdish forces have claimed that militants affiliated with the Islamic State group used a chlorine-based chemical in at least one suicide truck bomb in Iraq this year. Firing chemical mortar shells across distances, however, would be a new tactic for the group, and would require its munitions makers to overcome a significantly more difficult technical challenge.
In the clearest recent incident, a 120-mm chemical mortar shell struck a Kurdish position near the Mosul Dam on June 21 or 22, investigators said, and caused several Kurdish fighters to become ill.
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The shell was recovered nearly intact June 29 by Gregory Robin, a former French military ordnance-disposal technician. The tail of the shell had been broken, Robin said, and was leaking a liquid that emanated a powerful odor of chlorine and caused irritation to the airways and eyes.