If any weapons of the CBRN variety get used, it'll either be 1. a dirty bomb planted by the u.s. or u.s. allies (or a third party nation trying to gin up a fight between the u.s. and russia), and blamed on none other than putin 2. biologics because its an election year, covid, jab side effects, and economic collapse are all desperate for a distraction. Chemicals are out, because the last time that playbook was tried it failed to interest anyone, at all, and at that, it failed spectacularly, and nuclear is *probably* out, because while many involved are evil, most aren't insane.