Western strategists should proceed with the assumption that Russian use of CBW agents is likely. From the beginning of the Soviet state, only the thinnest veneer of deniability was required for extrajudicial terror. The pattern extends into foreign policy. Failure to appreciate this may cloud thinking that minimizes the possibility.
There are at least two ground situations, which currently exist, that facilitate the thinnest veneer, and a number of chemical agents / methods of application.
Prepare for the worst. A discussion in detail will follow.