You need to be a little more clear regarding the timeframe. Stalins Goal was a military "Alliance" with Poland. His Foreign Policy was basically an alliance with France, Britain and Poland with Russia being the dominant military force in eastern europe. After the Polish Invasion of Russia and the Battle of Warsaw in the mid 20's it pretty much became that restoring the polish territory to russia through outright military conquest wasnt going to work. Poland historically regarded russia not germany as its main enemy. Russias main threat was on its eastern borders without an active semi-war ongoing with japan. By encouraging hostilities between Poland and Germany russia could send in troops to "protect" the poles from germany with the backing of england and france and create a buffer between itself and germany. Once rusian tropps enter a country its very hard to get them out and i think they wouldve attempted to exert influence on the poles to remove Pilduski.

Interesting ideas, but some factual issues. Pilsudski removed himself in the mid-'30s. He died. Stalin knew full well that the Poles weren't going to work with him a bit diplomatically. If he wanted a buffer zone against the Nazis, then a more powerful Poland would have been a better asset than moving his own border westward. That's why Pilsudski launched the Kyiv Expedition in 1919 and invaded Ukraine - not Russia. There was an independent Ukraine at the time, with Hrushevskiy in power at one point and governments changing often. The idea was to install a pro-Polish government in Ukraine under Petlura and have a real buffer - an independent state with its own army - between him and some of the Russians. I'm not sure that Stalin was hoping for a West-Front stalemate - which damn near did bring out massive protests in western contries late in the war. And the invasion of France should have been a wake up call to him if he had been paying attention.

By the time of the invasion of France, Stalin's planned preparations would have been all made. No one, except perhaps Heinz Guderian would have expected France, the world's foremost military power, to effectively collapse after three weeks of fighting. Stalin had a non-aggression pact with Hitler and, at least it has been said, Hitler's original timetable had called for an invasion of Russia to be launched in 1944 which seemed to afford Stalin some breathing room to figure out how he would deal with Hitler. I may be wrong but I believe most people never really understood Heinz Guderian's blitzkrieg methodology even long after the war. Guderian was apparently convinced Hitler never did at the war's end. It is tempting to attribute to Stalin the same inability to adequately understand the threat that the almost scientifcally coordinated use of dive bombers, mechanized infantry and massed tanks posed to his army at the close of the Battle of France.