Earlier quoted context omitted.
What rational reason would Russia have to invade the Baltic States (or even for example Poland)? Even in best case scenario if the west does not directly intervene, they would get an additional few million people almost all of whom absolutely don't want to live in Russia and whom Russia could barely afford to police and a lot of additional economic sanctions. Also we're totally ignoring the internal political fallout…
They already have and the rest of the world just turned away, look at Crimea.
Geopolitically it made sense for the US and the West to largely ignore it. Due to their military presence there no one could argue that it wasn't Russia sphere of influence anyway. It was a small price to pay for ensuring that the the rest of Ukraine would shift it's alignment from Russia to EU/NATO (not having a Russian fleet stationed in one of your ports would likely make this move easier).
None of this in any way applies to the Baltic States.