The fundamental difference here is between a sovereign nation pursuing defensive alliances versus an aggressive invasion violating international law. Ukraine wasn't "amassing troops & missiles" at Russia's border as an hostile threat - it was seeking security guarantees after Russia had already annexed Crimea in 2014 and fomented separatist movements in eastern Ukraine. National sovereignty means countries get to determine their own security arrangements, and Russia's "security concerns" don't justify violating Ukraine's territorial integrity or dictating its foreign policy choices.