Why Did The Nazi Soviet Non-Aggression Pact?

The Nazi-Soviet Non-Aggression Pact was a strategic agreement between Germany and the Soviet Union. On August 14, 1939, Soviet Foreign Minister, Vyacheslav Molotov met with the Nazi foreign minister, Joachim von Ribbentrop in Moscow to discuss and arrange this pact. Nine days later the Nazi Soviet Non-Aggression Pact was signed. Briefly, the Nazi-Soviet Non-Aggression Pact stated that both countries would not attack one another neither individually or in collaboration with other powers and that one country does not have to support the other if attack by a third power. This treaty was to last 10 years and if neither party formally denounce the pact it shall automatically be extended for another five years. (http://www.britannica.com/EBchecked/topic/230972/German-Soviet-Nonaggression-Pact
During 1941 roads in Russia were generally unpaved and therefore were able to be easily manipulated by the elements. Due to Hitler’s delays, the German Army began its invasion against Russia at the end of June, leaving less than 2 months before Autumn, the rainy season, began. Summer roads in Russia were generally dry and sandy, which allowed for easy movement of foot soldiers. However, dust that had been stirred up through the air often became clogged in German tank filters, causing many tanks to be rendered unserviceable. These dust clouds not only helped to destroy German tanks but also allowed the Red Army to locate their enemy. With the enemies location the Red Army would then send out air attacks, causing serious losses to the German Army, in particular vehicles and horses. (http://www.allworldwars.com/Effects-of-Climate-on-Combat-in-European-Russia.html) However compared to other seasons Summer was one of the most manageable for the German
However during the second half of Autumn temperatures began to drop and the rain began to set in during mid October. The rain caused roads and surrounding land to be turned to mud, one of the largest obstacles during a war of movement and lasted for about a month. However though the muddy season was fairly short it had large effects upon the German army even in one case stopping an entire army from proceeding forward. Dirt roads were commonly impassable and supply trucks broke through the gravel-topped roads leaving the German armies using horse and cart to carry supplies from Germany and through Russia. The loss of German tanks and other motorised equipment was extremely high during the Autumn of 1941, with average of 1 tank surviving out of every ten. For example the second Panzer group lost 60% of it’s tanks by getting bogged down in the mud. This was a serious loss as no replacements were received. (http://www.allworldwars.com/Effects-of-Climate-on-Combat-in-European-Russia.html#III) The following quote, from the webiste All World Wars, depicts the advantage the Russian soldiers had during the muddy season. “The defender has time to organize his position well in advance of the muddy season. He can establish communications that enable him to shift reserves to threatened sectors. … Defending infantry can fight from