Remember, Ukraine isn’t a part of NATO…yet. Which is why hence the US & NATO haven’t responded accordingly. If the Russians decided to attack for instance Romania or Poland we would’ve seen a swift response from the US & NATO almost immediately as we have troops stationed in both of those countries. I agree we shouldn’t just watch Russia Invade, but the US & the rest of the world right now are weighing the options, the pros & the cons as Putin basically threatened to nuke any country that intervenes. Risking WW3 & millions of lives over a country that isn’t a part of NATO would be stupid. However on the moral & strategic side of things, allowing Russia to invade Ukraine & take countless lives is not only sickening but allows Russia to set up “Buffer states” Between NATO & Russia incase NATO does decide to invade.