The problem here is (again) that nobody wants to make Putin angry. Or sad. Or generally unhappy in any way whatsoever. I mean, nobody from the West. Russia basically says "Do what we want or we will do what we want anyway." And Obama and... Whoever it was on EU side just reply "Dude, that's not nice! But oh well, OK, if you insist. Just don't kick us in the nuts." That's a wrong way to go about it. It was wrong to begin with; on the first sign of Russian invasion of Crimea, NATO should be all like 'Hey, get out of there'. There should be a freaking aircraft carrier on the Black Sea, along with all the companions, not a single destroyer; offer of military assistance aimed at Ukraine as soon as any kind of invasion become even possible, and actual American* troops flying into Crimea way before the 'referendum'. Why? Because:
a) USA guaranteed that the Ukraine will stay intact after giving up nuclear weapons;
b) it is pretty much obvious to anybody with half a brain that _not_ doing that will just make Putin want more.
But it's not like the US can take any of it's military operations to the end. Not in Afghanistan, not in Iraq, not to mention things like Libya or Syria, so I wouldn't expect any better this time. Or next time.
Well, it will generally accomplish one thing - everybody will either give up or stack up military stuff. There are already voices in the Ukraine that the country should get some nukes back; in Poland there are talks about upping the army expenses, and so on.
*Yeah, I moved from NATO to just USA there, because let's admit it, it's not like the rest of the NATO could do much. As far as the EU goes, there is so little will to fight at all, that if not for the Americans, Russia would steamroll all the continent to Lisbon with less resistance than Hitler, due to populations just... Giving up. And the politicians are even worse here.