The Munich Agreement (1938) is the culmination of the helplessness of European diplomacy in front of the Nazi threat. This Munich conspiracy of European powers launched the largest war in history.
UK and France did not want to form an anti-Nazi alliance with the USSR, which forced Moscow to take maintain peace on its territory with its own forces.
This is a pro-Kremlin conspiracy narrative about the WWII.
The Munich Agreement (September 30, 1938), indeed, permitted German annexation of the Sudetenland, in western Czechoslovakia. The policy of appeasement towards Adolf Hitler was heavily criticized in Europe and proved to be a disastrous move. World War II began in Europe on 1 September 1939, when Germany invaded Poland. Great Britain and France responded by declaring war on Germany on 3 September.
A week before Germany attacked Poland, Hitler and Stalin signed a non-aggression pact, also known as the "Molotov-Ribbentrop Pact" (23 August 1939). The deal was accompanied by a secret supplementary protocol on the delimitation of areas of mutual interest in Eastern Europe. In particular, Hitler and Stalin agreed to divide Poland. The agreement also indicated that the Baltic states of Latvia, Estonia and Lithuania, as well as Bessarabia and Finland, also belonged to the respective areas of interest of Germany and the USSR.
Soviet Union attacked Poland on September 17, forcing the Polish army to fight on two fronts. Poland was divided according to the agreements of the Molotov-Ribbentrop pact. USSR later attacked Finland and annexed the Baltic states, all along the agreements with Nazi Germany.
USSR and Germany engaged in an intensive trade program, where Soviet Union provided Germany with grain and strategic raw material. More on the trade between Moscow and Berlin 1939 – 1941 here.
The war between the U.S.S.R. and Germany began on 22 June 1941, with the German invasion of the Soviet Union. The Soviet Union joined forces with the Allied Powers immediately after the German attack.