It's been well-known and established that the Syrians have had their own massive chemical weapons program for decades.
And also Saddam’s stock pile. Chemical weapons, actually, are no big deal. Mix chlorine with amonia and you’ve got a chemical weapon. Nerve gas is extremely similar to bug spray. I once had a small dog that I applied too much flea poison to her skin. She became ill, so I brought her to a vet, and he injected her with atropine, same as for nerve gas. Biological and nuclear are the real worry.