 Despite the parties ' ostensibly cordial relations , each side was highly suspicious of the other 's intentions . After Germany entered the Axis Pact with Japan and Italy , it began negotiations about a potential Soviet entry into the pact . After two days of negotiations in Berlin from 12 to 14 November 1940 , Germany presented a written proposal for a Soviet entry into the Axis . On 25 November 1940 , the Soviet Union offered a written counter @-@ proposal to join the Axis if Germany would agree to refrain from interference in the Soviet Union 's sphere of influence , but Germany did not respond . As both sides began colliding with each other in Eastern Europe , conflict appeared more likely , although they did sign a border and commercial agreement addressing several open issues in January 1941 . Historian Robert Service avows that Soviet leader Joseph Stalin was convinced that the overall military strength of the USSR was such that he had nothing to fear and anticipated an easy victory should Germany attack ; moreover , Stalin believed that since the Germans were still fighting the British in the west , Hitler would be unlikely to open up a two front war and subsequently delayed the reconstruction of defensive fortifications in the border regions . When German soldiers swam across the Bug River to warn the Red Army of an impending attack , they were treated like enemy agents and shot . Some historians believe that Stalin , despite providing an amicable front to Hitler , did not wish to remain allies with Germany . Rather , Stalin might have had intentions to break off from Germany and proceed with his own campaign against Germany to be followed by one against the rest of Europe . 
