The Soviet Army had never stood down after WW2 ended. Stalin was planning to exile all Jews to Siberia and intensify a massive purge that would be the final rupture with the West and bring on another World War he thought they were sure to win.
What is certain is that before Yalta, Stalin was unsure whether or not his plans to seize Eastern Europe would be militarily opposed by the Allies and was very cautious.
By Potsdam he abandoned everything but the pretense.
He saw that the UK was used up, that the US would not commit ground troops for an anti-Soviet war and that France would not lift a finger to help her allies. He also saw that the US did not relish using its weapons of mass destruction, while he himself exulted in the most extreme savagery.
If Stalin had gone to war to conquer all of Europe, except Britain, it is doubtful that the US would have stood in their way.