Why were concessions made to the soviet union in eastern europe and asia

Because we were far more willing to let the Red Army bear most of the Allied casualties of World War II than to push British and American troops into Eastern Europe and Manchuria. The Russians were already breaking into Poland and Hungary by the time of the D-Day landings. It's a question of how many casualties we were willing to take in the whole war, and how would we dislodge the Soviet forces from places they already held.