Russia was an ally 1941-1947 approximately. Also, an ally with Germany 1940-1941.
The Soviet Union was an ally from 1941 to 1945 - but only in Europe; they observed a ceasefire with Japan until the last weeks of the war, when they grabbed territory in the east and set the groundwork for the fall of China, the Korean War, and the Vietnam War.
Considering their actions from 1936 to 1941 (in Spain and the Baltics, Poland), our alliance with them is a source of great shame (and eastern Europe never forgot it).