Why Russia entered World War 2?
The USSR entered WWII as a result of Operation Barbarossa, the German invasion of the Soviets.
In World war 2 the British were fighting on the allies side Russia (the Soviet Union at the time), and France. After Russia dropped out of the war because of their own revolution, the United States entered on the side of Britain and France. They were fighting against the Axis Powers of Japan and Germany.
If Japan had invaded Russia from the East to help Germany instead of attacking the US would that of changed the outcome of World War 2?
The U.S entered World War 2 , right after the Japanesse bombed the U.S. at Pearl Harbor. President Roosevelt was very anger with Japaneese empire , so he entered World War 2 to get back at the Japan Empire. Also we entered the war to help our allies (the British and French) to take down the Nazis who were trying to control all of Europe at the time
For all practical purposes the Europeans early in WW 2 were shaken by Hitler's Blitzkrieg. Later when the US entered the war, the new western allies were able to push back German forces completely out of France. In WW 1 this was never possible.The Soviets, unlike Russia in WW1 were able to counter attack the German invasion in Russia. The combined WW 2 allied success in WW 2 was totally different than in WW 1.