ISIS used mustard gas in a battle against Kurdish forces in Iraq, a chemical weapons watchdog confirmed.
The group, Organisation for the Prohibition of Chemical Weapons, told Reuters laboratory tests confirmed ISIS had used sulfur mustard during a November 2015 battle against Kurdish fighters in Iraq. It marks the first time chemical weapons have been used in the country since the fall of Iraqi dictator Saddam Hussein in 2003, the news agency reported.
Samples were taken from 35 Kurdish fighters who became sick after battling ISIS militants in northern Iraq's autonomous Kurdish region.
It's the second time laboratory tests have proven that ISIS used chemical weapons. In October, the OPCW revealed “with the utmost confidence that at least two people were exposed to sulfur mustard” in Syria. In that engagement, ISIS was fighting against a rebel group for control over a Syrian town. A baby was among the casualties, Reuters reported.
“It is very likely that the effects of sulfur mustard resulted in the death of a baby,” the OPCW concluded in a report dated Oct. 29, 2015.
At the time, diplomatic sources who spoke to Reuters on condition of anonymity said they were concerned about the possibility that ISIS militants had developed the ability to make a crude form of mustard gas on their own.
“It raises the major question of where the sulfur mustard came from,” a source told Reuters. “Either [ISIS] gained the ability to make it themselves, or it may have come from an undeclared stockpile overtaken by IS[IS]. Both are worrying options.”
Officials said the latter scenario was a possibility, as large swaths of Syria have changed hands between ISIS and the official Syrian government loyal to President Bashar Assad since the country's civil war began in 2011. At various points since then, as much as 60 percent of Syria -- by land mass -- was in control of ISIS.
Mustard gas was first developed by German scientists and deployed during World War I, according to LiveScience. Named because of its odor, which is reminiscent of mustard or horseradish, the chemical agent can cause severe burning and blistering of the skin and lungs. It was initially intended to incapacitate large numbers of enemy combatants by causing the physical reactions, as well as temporary blindness and shortness of breath.
Most victims don't exhibit symptoms until 12 to 24 hours after exposure, according to LiveScience, but larger doses of mustard gas can cause severe reactions within an hour or two. Mustard sulfur isn't immediately fatal, but can disfigure and kill in the long term if victims are exposed to large amounts of the weaponized chemical.
Among those who believe ISIS is manufacturing its own mustard gas is Hamish de Bretton-Gordon, a biological and chemical warfare specialist who spoke to Reuters.
"I'm pretty convinced that the mustard IS[IS] are using in Iraq is made by them in Mosul, [Iraq]," Bretton-Gordon said. "They have all the precursors at hand from the oil industry and all the experts at hand to do it."