It's a good question when that happens. And if we knew for sure that that was what was happening here the moral calculus would be clear. But we don't know for s

It's a good question when that happens. And if we knew for sure that that was what was happening here the moral calculus would be clear. But we don't know for sure. I think because we live in the shadow of WWII and because states so disproportionately educate their children about WWII that we often overestimate how often that kind of moral imperative rears its head. For every time in history that a country invaded another with the intent of total domination there are a hundered times when countries invaded other countries in a limited way, to shore up their frontiers, to affect a balance of power, to acquire a spcific resource, or to satisfy some portion of their population. Limiting Russia's ambitions doesn't make this kind of thing less of a crime. Our commitment to self-determination and anti-colonialism that we inherited from those who fought WWII shouldn't waiver. However, we should be cautious to discuss everything in the existentialist terms of WWII. America's last 70 years of war making should teach us that if anything. There is no shortcut to moral clarity in foreign affairs. Unfortunately you can't achieve justification of violence without letting the belligerents show themselves prove its necessity.