Operation Barbarossa Prevented Stalin's Invasion Of Europe
A number of Russian historians have come to the conclusion that Stalin was preparing to invade Germany and Romania and with his Operation Barbarossa Hitler beat him to the punch. The code name for this invasion was Operatsiya Groza (Operation Thunderstorm). Two of the Russian historians who support this are Viktor Suvorov http://en.wikipedia.org/wiki/Viktor_Suvorovand Igor Bunich http://en.wikipedia.org/wiki/Igor_Bunich
It is simply not true to say that the USSR was neutral until the German invasion. In 1939 the Soviet Union invaded Poland and Finland, in 1940 Estonia, Latvia, Lithuania and Romania and even after the soviet-nazi war started invaded Iran in 1941. A thread on Operation Barbarossa being a preventive attack - http://forum.codoh.com/viewtopic.php?f=20&t=7999