ISIS used Mustard Gas against Kurdish forces...Confirmed.

via Reuters.

Islamic State militants attacked Kurdish forces in Iraq with mustard gas last year, in the first known use of chemical weapons in Iraq since the fall of Saddam Hussein, a diplomat said, after tests by the global chemical arms watchdog.
A source at the Organization for the Prohibition of Chemical Weapons (OPCW) confirmed that laboratory tests had come back positive for the sulfur mustard, after around 35 Kurdish troops were sickened on the battlefield last August.
The OPCW will not identify who used the chemical agent. But the diplomat, speaking on condition of anonymity because the findings have not yet been released, said the result confirmed that chemical weapons had been used by Islamic State fighters.

The samples were taken after the soldiers became ill during fighting against Islamic State militants southwest of Erbil, capital of Iraq's autonomous Kurdish region.

Well this is interesting.  We've always suspected they had chemical weapons (or at least have suspected for awhile now) but this puts things in a different category.

First the threat to Europe is obvious.  If they use smuggling routes through Turkey to launch a strike in Paris, Copenhagen, or even London then its going to be Katy bar the door.

Second, if the US does put troops on the ground and ISIS launches chemical strikes then I believe (not sure) that at one time that would require a nuclear retaliation.

ISIS is anything but boring.