This is a bad analogy. First of all, we have nukes. Why would we care if Russian troops showed up on the border. If they cross that line, their country gets wi

This is a bad analogy. First of all, we have nukes. Why would we care if Russian troops showed up on the border. If they cross that line, their country gets wiped off the map. The same dynamic exists with Ukraine and Russia. Also, you analogy completely ignores the economic relationships that the West has been trying to build with Russia for the last few decades. Western doctrine has been largely focused on building international trade and economic relationships as a method for maintaining peace. There is a reason we exported a good chunk of our manufacturing after all. The only way your analogy holds is if Russia and Canada had been spending decades trying to build peaceful economic relationships with the US. And they openly express little interest in invading the US. But then the US starts saber rattling at Canada and claims that they feel their security is threatened. I think most people would agree that the US is behaving belligerently in that scenario and that Canada would be justified in building up defenses.