1940 that was over four times larger than the one the two countries had signed in August 1939, providing for millions of tons of shipment to Germany of oil, foodstuffs and other key raw materials, in exchange for German war machines and other equipment. This was followed by a January 10, 1941, agreement setting several ongoing issues, including border specificity, ethnic migrations and further commercial deal expansion. Discussions in the fall and winter of 1940–41 ensued regarding the potential entry of the Soviet Union as the fourth members of the Axis powers. The countries never came to an agreement on the issue. Aftermath German invasion of the Soviet Union Nazi Germany terminated the Molotov–Ribbentrop Pact with its invasion of the Soviet Union in Operation Barbarossa on June 22, 1941. After the launch of the invasion, the territories gained by the Soviet Union due to the Molotov–Ribbentrop Pact were lost in a matter of weeks. In the three weeks following the Pact's breaking, attempting to defend against large German advances, the Soviet Union suffered 750,000 casualties, and lost 10,000 tanks and 4,000 aircraft. Within six months, the Soviet military had suffered 4.3 million casualties and the Germans had captured three million Soviet prisoners, two million of which would die in German captivity by February 1942. German forces had advanced 1,050 miles (1,690 kilometers), and maintained a linearly-measured front of 1,900 miles (3,058 kilometers). Post-war commentary regarding Pact negotiations The reasons behind signing the pact There is no consensus among historians regarding the reasons that prompted the Soviet Union to sign the pact with Nazi Germany. According to Ericson, the opinions "have ranged from seeing the Soviets as far-sighted anti-Nazis, to seeing them as reluctant appeasers, as cautious expansionists, or as active aggressors and blackmailers". Edward Hallett Carr argued that it was necessary to enter into a non-aggression pact to buy time, since the Soviet Union was not in a position to fight a war in 1939, and needed at least three years to prepare. He stated: "In return for non-intervention Stalin secured a breathing space of immunity from German attack." According to Carr, the "bastion" created by means of the Pact, "was and could only be, a line of defense against potential German attack." An important advantage (projected by Carr) was that "if Soviet Russia had eventually to fight Hitler, the Western Powers would already be involved." However, during the last