That's all pretty besides the point, though. In the extremely unlikely event Putin decides to take the Baltics, I see one of 2 strategies he would employ, because fighting us in the kind of war you're describing is a losing battle for him and he knows it. He's not stupid. He will either use hybrid warfare on the model of how he took Crimea and Eastern Ukraine, meaning no real troops in uniform and no invasion per se. In this case, we would have to decide if they were actually attacked or not, and whether article 5 even applies. The 2nd scenario is that Putin does invade but is fully prepared to use tactical nukes to level the playing field, probably betting that we don't have the stomach to use nukes back. This is far less likely, but more likely than him thinking he's just going to pit his conventional military against the Western world and keep nukes out of it.