Who has chemical weapons.?

Assume many do. If any government or crackpot group were to use chemical weapons on their enemies today, the full wrath of all the civilized nations and most of the not-very-civilized nations would come down on them. A single kook could spray a bus with phosgene or a nut cult could kill a few dozen people in a city. These people are crazy but not stupid and realize that this would be self-defeating.