Western participation kind of puzzles me, too. The Soviets were for the Nazis before they were against them. They made the German invasion of Central and Western Europe possible, by ensuring that the German armies had a steady supply of Soviet goods to keep them going, and provided the Germans with a secure Eastern front. In the modern era, it was the mother of all blowbacks - a lot similar to the Sung empire’s decision to use the Mongols against the Western Hsia and Chin empires in the 13th century.
You ain't seen nuthin' yet...
Obama expands outreach to Muslim world with entrepreneurship summit
The reason for US participation, you only have to look who is occupying the White House. It is his way to salute Communism.
Not only that, but Soviet History pretty much omits the western allies contribution to their victory in the "Great Patriotic War." Wonder how their explaining this to the kids?