I would wager it would be a lot harder to find willing soldiers if chemical/biological weapons were more widespread.
Let's face it they could be more useful than nukes. If you develop a highly toxic agent that kills quickly, and neutralises itself from the environment in a reasonable space of time it's the perfect weapon. All the infrastructure is kept in place, zero property damage. Ready for you to move into. Win win. I'm sure a lot of countries including our own are working on that behind closed doors.
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