You must be familiar with this
Text of the Nazi-Soviet Non-Aggression Pact
http://legacy.fordham.edu/halsall/mod/1939pact.html
If Hitler and Stalin signed a pact then it follows Hitler was not claiming to defend the world against communism....
More here
THE MOLOTOV-RIBBENTROP PACT OF 1939:
LEGAL AND POLITICAL CONSEQUENCES
http://www.lituanus.org/1989/89_2_02.htm