As a Libertarian I hate Putin. I also hate the fact that people seriously care about Crimea. I don't want to defend Putin, but what he does in Russia's sperhe of influence isn't a serious threat unless he invades a NATO country.
Spheres of influence are an outdated concept IMO. Bigger nations shouldn't be entitled to harass smaller nations that happen to be nearby. If Ukraine wants to ally with the US, it should be allowed to do so without fear of invasion, just as any Central or South American nation should be allowed to ally with Russia without fear of American attack.