The demographics of the Russian army would skew heavily to poor people from the provinces (particularly ethnic “republics”) and those who couldn’t manage to get out of military service (something you try to do if you’re Russian and have any sense of self-preservation), so their English-language skills would probably be worse than the average Russian. Though there’s the off-chance that, among every thousand or so troops, there’d be one or two who picked up English from rap songs or pirated movies, or grew up in a relatively privileged environment and was exposed to it but somehow ended up having terrible luck after that.

In North Korea, I doubt anyone speaks it who isn’t a trained intelligence officer of some sort (including hackers and the handful of tourist guides). They wouldn’t teach the language of the imperialists in their schools, and just having materials in English could probably land you in the gulag.