IS Suspected Of Chemical Attack On Kurds In Iraq
German officials say Kurdish troops suffered breathing difficulties after an attack near the city of Irbil earlier this month.
They did not mention what may have been used but U.S. officials told local media that they believe it was mustard agent.
U.S. officials said that the IS could have obtained the mustard agent in neighbouring Syria.
IS has previously been accused of using chlorine gas against Kurdish fighters.
Chlorine is a choking agent whose use as a chemical weapon dates back to World War One. It is banned under the 1997 Chemical Weapons Convention, which prohibits all use of toxic agents on the battlefield.