1. The US singlehandedly won World War II in Europe with a little help from Great Britain
2. Japan surrendered because of the atom bomb attacks on Hiroshima and Nagasaki
Here's the reality...
1. Hitler invaded Russia in 1941.
Here's what politician, not President Harry Truman, said about it:
"If the Russians are winning we ought to help the Germans, and if the Germans are winning we ought to help the Russians, and that way let them both kill each other."
2. Russia completely chewed up the German military at great cost to itself
3. Three months after the German surrender in Europe on August 8, 1945, Russia joined the war against Japan driving them from Manchuria, Inner Mongolia, Northern Korea, and assorted north Pacific Islands.
To accomplish this, Russian forces completely rolled over, defeated and received the formal surrender of The Kwantung Army, the largest and most prestigious command in the Imperial Japanese Army.
The Japanese surrendered seven days later.
No one says Stalin was an admirable person, but the historical record shows that Russia inflicted exponentially more damage on the Nazis and recovered more conquered territory than Allied forces led by the US.