I'm pretty sure all that would happen is a bunch of outraged Russians would wait until it gets cold to steamroll you from across the urals and from all their industrial centers along the southern border, encircle Moscow, siege it, and then push you back out after half the survivors have eaten the other half to avoid starving to death.
As for the idea of a naval blockade...fucking lol. It is fucking Russia. Just think of all the border troubles say US has with interdicting things and people from Mexico. Now multiply that by like 20 and make it a dozen nations instead of just one. I don't think Russiand even rely on naval based imports much at all to begin with. You'd have to bomb the rail and to do that you're going to somehow need to form a coalition with fucktons of Central Asian countries, Caucasus, and butthurt belters to all agree on letting you somehow try to police flow of supplies into Russia. Oh yeah, and also China, which is responsible for I think the bulk of Russian foreign business relations particularly materials.
You'd need to not just capture Moscow and st Petersburg but also a bunch of cities all along the southern edge, which has been centers of everything from major industry to Russian space program to secret weapons labs since the Soviets. If you took the southern rim along with the entire West of Russia then yeah, you could probably conquer Russia enough that what's left in the interior couldn't do much but guerilla raids.