The key difference is that the Baltic states are all full members of NATO. Even as cautious an American President as Obama couldn't let that go. We and the French would force the American hand, I suspect.Like SUTSS, I don't think the annexation of the Crimea will be the end of this. As Russia's border is pretty indefensible due to its sheer size their policy historically has been to surround themselves with buffer states and Putin may well be looking to do this again. He is clearly trying to foment discord across Europe by funding extreme parties on both the right, see the National Front in France and also Hungary, and on the far left, possibly Syriza in Greece (although I'm not too sure about that one). I reckon in Putin's eyes he is already at war with the West, in 2008 they invaded South Ossetia in Georgia and more recently Crimea. The Baltic states, with their sizable Russian minorities, must be feeling very nervous right now... I wouldn't be surprised if within a few years we see the same happening there with some excuse about "protecting Russian minorities" or something about creating a path to Kaliningrad.
They did indeed, but I think a repeat unlikely. The last time the Russians had few good officers and no winter gear but still made good gains. I wouldn't fancy taking a fight with Russia these days. Fuq datAmbitious. Finland handed them their arse last time.