They may have later. You are making all sorts of assumptions not based on any facts
Apparently you don't care much either way since every bit of the information out so far has come either openly from the ISIS Muzzies who are known for their random violence and cruelty or not openly to Trump & company from the same Intelligence people who have been lying under oath, spreading baseless lies, and leaking all sorts of half truths about Trump, since the day he was sworn in.
Fine with me if you don't know the answer to something, but just say you don't know instead of pretending that any question you don't like is based on assumptions. There are plenty of chemical agents that could have been used that wouldn't require proctive gear, maybe it was one of those, maybe not.