With all due respect you're confusing diplomacy with morality. The question isn't if Socrates would find the behavior pleasingly moral, but if pragmatically at least one country has been invading random 3rd world countries on the other side of the planet for decades without the world collapsing into WW3 then what is the likely outcome of a much more minor ... international misbehavior. Therefore a country "invading" direct neighbors who historically have always been part of the empire is extremely unlikely in a pragmatic analysis to cause geopolitical instability or WW3 or whatever warhark ridiculousness.
Don't get me wrong, it can still be morally and ethically "wrong" in an abstract sense. But most people are concerned with the fearmongering "Oh no, Russian tanks will be rolling down the boulevard in Paris next year unless we ..." is all completely ridiculous. Russia already fought and lost a COIN "Vietnam" against a majority Islamic nation of Afghanistan, once demographic replacement takes hold Russia isn't going to want a piece of France or Germany even if handed to them on a plate, oh no last thing they want is the suburbs of Paris in revolt as usual.
The Russian Bear has been content to be contained in its den, as long as its not poked, for centuries. The odds of the Russians regime changing Mexico and fighting a failing counter insurgency in Mexico on our border for decades is approximately zero, like space aliens landing on the white house lawn is a more realistic concern. There are world wide geopolitical problems, none of which involve the Russians.
As a land empire on the other side of the planet, with people more or less like us, following a religion more or less like ours, and a economic system vaguely similar enough, a space alien would assume the Russians should be our closest ally... and if it were not for unfortunate temporary historical anomalies they almost certainly would be. In an unperturbed system (LOL as if international diplomacy has ever been that) they would be great allies.