Were the situation reversed, and Russian weapons would be allowed on US targets from, say, Mexico, how would we respond militarily?
We haven’t invaded Mexico, in case you are not aware of that.
When Europe burns the world burns, tens of millions die and they are called world wars and the end of the humanity is constantly in the balance.
Canada, the U.S., and Mexico have nothing to do with global madness and the world has no role or requirement for survival here.