American officials believe ISIS likely used chemical weapons in Iraq on Wednesday, a development that for the first time indicates the militant group has obtained outlawed chemical weapons. Kurdish forces fighting ISIS in northern Iraq reported difficulty breathing following an ISIS attack, a worrying sign generally considered an indication of chemical weapons use. U.S. officials believe mustard gas was the chemical agent used.
“The use of mustard agent would mark an upgrade in Islamic State’s battlefield capabilities, and a worrisome one given U.S. intelligence fears about hidden caches of chemical weapons in Syria, where Islamic State controls wide swaths of territory,” according to the Wall Street Journal. “Mustard agent, first employed as a weapon in World War I, can cause painful burns and blisters, immobilizing those affected by it, but it is usually deadly only if used in large quantities.”
It is not immediately clear where ISIS obtained the mustard gas, but the group controls large amounts of territory in Syria and Iraq and both countries are thought to have old chemical weapons caches. Officials tell CNN ISIS likely delivered the mustard gas using a mortar or rocket shell.