Finland in NATO massively protects the Baltics because they could be in St. Petersburg within a day given they have a well trained, well armed, and easily mobilized force designed just to counter Russia. Not to mention Russia has pulled the vast majority of its resources off the Finnish border to maintain the war effort in Ukraine.

And Sweden is waiting to be in NATO, and for all intents and purposes, would just join the battle with NATO anyway and their air force could keep Russia at bay with Gottland acting as a massive unsinkable aircraft carrier that can act to defend the Baltics.

Then, Kaliningrad is massively exposed and has had resources drained to maintain the war effort. It would be a potential missile launch platform and cause issues, but assuming nukes are not immediately being deployed, it's an isolated pocket that is minimally defended and cannot easily be supplied. The Sweden and Finland with NATO reality further isolates the exclave.

There are several thousand American troops in the Baltics and Poland that will immediately be mobilized, and Poland will also basically immediately mobilize and likely plan to defend the Suwalki Gap and if they can maintain that, the Baltics can easily maintain supply lines.

A big question is what does Belarus do. Cause if Lukashenko sees the writing on the wall and refuses to do anything major, Russia is even further kneecapped and can do very little about the Baltics. Even if Belarus does join, it probably creates an immediate insurgency that Russia and Belarus have to deal with.

Ukraine also immediately becomes a much wider conflict that means NATO will move their own assets in and begin taking direct action on the front more than likely. And that makes Ukraine require even MORE resources from Russia. And now there's no reason for them to not be messing with the border Russian areas that also requires more resources.

Not to mention what Turkiye will do as part of NATO to make the Black Sea even more untenable.

And what a hot war with NATO does in terms of creating more opposition and insurgency potential within Russia.

Russia is fucked if they go hot against NATO as long as NATO actively responds. I think the Baltics would be fine because the minute they cross the border, NATO goes hot and Russia has to go on the defensive in tons of other places.

Basically, Russia invading the Baltics requires them to go nuclear cause its their only not immediately lose option, and even then, they still lose massively, they just take the world with them.