The Islamic State appears to have manufactured rudimentary chemical warfare shells and attacked Kurdish positions in Iraq and Syria with them as many as three times in recent weeks, according to field investigators, Kurdish officials and a Western ordnance disposal technician who examined the incidents and recovered one of the shells.
The development, which the investigators said involved toxic industrial or agricultural chemicals repurposed as weapons, signaled a potential escalation of the group’s capabilities, though it was not entirely without precedent.
Beginning more than a decade ago, Sunni militants in Iraq have occasionally used chlorine or old chemical warfare shells in makeshift bombs against American and Iraqi government forces. And Kurdish forces have claimed that militants affiliated with the Islamic State, also known as ISIS or ISIL, used a chlorine-based chemical in at least one suicide truck bomb in Iraq this year.
Firing chemical mortar shells across distances, however, as opposed to dispersing toxic chemicals via truck bombs or stationary devices, would be a new tactic for the group, and would require its munitions makers to overcome a significantly more difficult technical challenge.
Chemical weapons, internationally condemned and banned in most of the world, are often less lethal than conventional munitions, including when used in improvised fashion. But they are indiscriminate by nature and difficult to defend against without specialized equipment — traits that lend them potent psychological and political effects.
In the clearest recent incident, a 120-millimeter chemical mortar shell struck sandbag fortifications at a Kurdish military position near Mosul Dam on June 21 or 22, the investigators said, and caused several Kurdish fighters near where it landed to become ill.
The shell did not explode and was recovered nearly intact on June 29 by Gregory Robin, a former French military ordnance disposal technician who now works for Sahan Research, a think tank partnered with Conflict Armament Research, a private organization that has been documenting and tracing weapons used in the conflict. Both research groups are registered in Britain.
The tail of the shell had been broken, Mr. Robin said by telephone on Friday, and was leaking a liquid that emanated a powerful odor of chlorine and caused irritation to the airways and eyes.
It was the first time, according to Mr. Robin and James Bevan, the director of Conflict Armament Research, that such a shell had been found in the conflict.
In an internal report to the Kurdish government in Iraq, the research groups noted that the mortar shell appeared to have been manufactured in an “ISIS workshop by casting iron into mold method. The mortar contains a warhead filled with a chemical agent, most probably chlorine.” …