At this point the war was inevitable, and turning a blind eye would probably just embolden Russia even more - better to let them meet real resistance in outside

At this point the war was inevitable, and turning a blind eye would probably just embolden Russia even more - better to let them meet real resistance in outsider-Ukraine, compared to directly fighting them in some NATO country, like one of the Baltic countries. Not to mention the signal that would send to China. If one of the goals to the US gov. is to also save American lives, then obviously a proxy war is more favorable than a direct conflict. Not doing anything at all was never an option for the US - sans of having a Russian puppet ruler as president, and deliberately going for isolationism.