The Yalta conference was held after the WWII in 1945, where some of the themes were the division of Germany into interest zones, as well as the recovery of nations that were occupied and destroyed by Germany. Churchill, Roosevelt and Stalin participated in the conference, and it was decided that democratic elections should be provided to all nations, and this obligation was published as a common Declaration on Liberated Europe. Stalin was offered a sphere of influence in Eastern Europe.
The answer is: Joseph Stalin.