Note: this thread was not entirely what I expected from the title...
I've been posting up an epic chronological re-sorting of Viktor Suvorov's Icebreaker Thesis (since his two English books on the topic aren't sorted chronologically very well, which makes his theory harder to analyze), over in the prior forum, for the past several months (as some of you may already know). So I can drop in some points relevant from that thesis.
At VE Day, Stalin has the following situational pros and cons:
Pros.) He has a stupidly large and very well equipped army, arguably better in its quality than what the Western Allies are fielding. (The Nazis certainly thought so.) And Stalin has been aiming to take over Germany and thence Europe (and then the world, mua ha ha ha haaaa) since before Stalin even got control of Lenin's power in the late 20s. So, he has the motivation to keep going. But his military's size and quality, and his experienced higher officers, are the only things he currently has in his favor.
Cons.) His stupidly large army has a dangerously high proportion of very green troops right now, for various reasons. (Something the Nazis were also aware of.) The Western allies have a much higher proportion of veterans, using equipment not much worse (if any) than his, and they'd be on the defensive which would mitigate his numerical advantages. (Presumably the pickups of German troops and equipment from either side would be about equal.) Also, Stalin won't be able to catch them out of position in a surprise blitzkrieg, which has been his overarching grand strategy for literally decades in preparation, and which he's certainly still thinking about because he quickly sends a large blitz operation over to Mongolia again (larger than his first blitz op in August 1939) to start picking up much easier property-and-means-of-production in China and South-east Asia. (Not so much where the Japanese are still defending.)
He does have more backfield to trade for time on the defensive, if Patton (for example) decides to attack, but that isn't the same as going on the offensive. And even then, the defensive characteristics of his backfield have been largely ruined, not only by years of East Front war, but also by Stalin himself starting in September 1939.
Relatedly, his logistic support in western Russia is a mess (after so many years of war), and moreso in the Eastern Europe border nations he has recently overrun, where he hasn't even had some time to start trying to repair it.
Moreover, Stalin badly needs to shift troops back to being workers again for a protracted period. On June 21st, 1941, Stalin had been about to fatally cripple the Soviet Union with too many troops mobilized to do any reasonable amount of harvesting (after two years of limited harvests in mobilization) -- the Soviet Union was about to starve to death (as an organized government anyway) unless he either went somewhere to get more food and perishable resources, or else unless suddenly he had a whole lot less mouths to feed one way or another. Starting one day later, the latter option happened.
But now he's in a similar situation and the rest of Europe is in no position to loot food from to feed his armies (and then the rest of his workers). Which also explains why he was more willing to shift military ops over to his eastern regions: easier and more profitable looting over there, for the moment.
Overall, not only does a continuation of operations into the rest of Europe look dicey as hell, and risking a potentially fatal counter-thrust (or pre-emptive thrust) by the western Allies if they feel provoked, but even if he succeeded he might face serious revolution in his backfield from being unable to feed and supply his people (and his troops) by looting Europe, assuming (as would have seemed probable) that the western armies would have been able to at least protect their own food and short-term supply sources: the only good supply of such things in the area right then. (At VE-Day the nukes haven't been dropped yet, but he knows from his intelligence services they're in development and that potential capability would factor, too.) And his risk of his government collapsing into a new Civil War isn't much better if he stays too mobilized up on the border without doing anything.
But if he stands down enough to send his troops somewhere else to loot while his other troops demobilize back into production and other essentials short-term production, then he runs the risk of facing settled and alert defenses later which he'd be unable to surprise-blitz. But he can't really do that anyway, anymore, in the short run either, so his best shot is to play for time, agitate his neighbors internally, and watch for opportunities. Thus setting up the early Cold War.