It’s just what the headline says, confirmed by the Pentagon:
Pentagon officials are aware of rocket and mortar attacks using the blistering agent mustard after samples from four locations in the region were analyzed, said defense officials familiar with details of the assessment.
Few details have been released of the confirmed use of chemical arms. However, officials said the chemical agent appears to have been manufactured from chemicals obtained by the Islamic State (IS), also known as ISIS or ISIL, and did not appear to be from current or older chemical weapons stockpiles kept in either Syria or Iraq. [Emphasis added, because damn.]
Still the jayvee, Mr President?
We’re long past time for action, serious action, against the Caliphate.