If you were Stalin, what would you do when your Plan A is dead? You know war is coming, you believe Hitler when he says his aim is to seize lebensraum to the east. Your potential allies don’t get it. What would you do? While London and Paris dither and Warsaw dreams dreams (what dreams? Hitler just tore up the non-aggression pact you were counting on: you’re next) Hitler strikes. How about a non-aggression pact? Stalin seizes the chance, the agreement is immediately signed. Stalin knows perfectly well that Hitler is going to attack the USSR and so he starts to grab as much territory to the west as he can and put off the day as long as possible.
