Also it seems rather unhistoric the movie you described. The finns were actually on the nazis side in WWII. The Sovjet union were their common enemy. It might have occurred something like it before the Sovjetunionen entered the war in june 1941 The winter war was fought between just Finland and Sovjet until peace in march 1940 but in 1941 they contined the war as allies to Germany. Thats called the continuation war.