This study makes use not only of German documents captured during the Second World War but of personal accounts of major figures of the Third Reich and their testimony at the Nuremberg Trials. Organized into five chapters, this study surveys Nazi- Soviet relations from 1939 to 1941, from the German viewpoint, with emphasis on Adolf Hitler's assessment of Russian policies and Germany's wartime situation, both of which factors shaped his decision to invade the USSR. The conclusion is that Hitler saw his attack on the Soviet Union as a preventive war, carried out to destroy a growing threat to the Reich. He interpreted Russian activities during the period 1939-1941 as designed to strengthen the USSR strategically against Germany in preparation for intervention in the ongoing conflict with Britain.