The thing is there are not going to be missiles in Canada or Mexico. Cuba maybe. Venezuela maybe.
But it’s patently absurd to suggest that Mexico or Canada would host Russian or Chinese nukes.
I will concede that if Quebec were independent then yeah, those jerks might do this.
It's a "put yourself in another mans shoes" analogy. It takes you out of thinking of Putin as an evil madman (i.e. emotionally) and instead thinking through the possible concerns motivations he might have so you can decide objectively if they hold water. What if China built a biolab in Tijuana or maybe more credibly a fentanyl factory?
Note that I don't think Russia invading Ukraine had anything to do with biolabs. I think it had to do with expansion of NATO into Ukraine which would guarantee a hostile government there for the foreseeable future. Remember when for 200 years America held to the Monroe Doctrine predicated on the concept that European colonization within the Western Hemisphere would be considered a hostile act against the USA? If the USA could have official policy for 200 years that a European power colonizing, say, Peru, would be considered a hostile act against the USA, is it possible that Russia might be justified in having a similar position vis-a-vis NATO expansion right up to the Russian border? Note: The Monroe doctrine was meant as a warning, a deterrent. It was never used to open a war pre-emptively. Hence yes, this analogy is imperfect too. Such is life.
Just things to ponder.