True,but when have US or British troops used chemical or biological weapons in combat.
Ooooooo thats a hard one , is it never , a few times , hundreds of times or many many thousands of times

Even freaking tear gas is illegal under international law. Tear gas?
Is it ?
Yeah I suppose it is if all parties have signed and ratified the treaty and all the opt out clauses many states added don't apply then yes it would be illegal , if not they revert to the earlier treaty where it is not illegal .