Unless things have changed drastically since my days in the military, the Army had both CS and CN grenades, plus other means of deploying those agents. Both of those, incidently, were used in SE Asia during that unpleasantness, mostly by the "tunnel rats".
Poison gas, such as mustard, phosgene, VX, etc., are proscribed by the Geneva Convention and the Hague Accord under the "Laws of Land Warfare". CS and CN, while very unpleasant and incapacitating, are, with rare exceptions, non-injurious. Persons with respiratory or gastrointestinal issues should be exposed to neither agent.
Btw, CN will make you think you are going to bring up meals you ate twenty years ago.
Only reason I know this much is I had to teach a class on the Law of Land Warfare. I also was exposed, in training, to both those agents. Neither is a pleasant experience.
From what I understand, neither the tear gas (CS) or the pepper spray used by police is as strong as that used by the military.
Some of you with more recent military experience may be able to shed much more light on the subject.