1) In the interwar period following WWI, new governments led by authoritarian leaders rose in Germany, Italy, Japan, and the Soviet Union under Stalin. 2) The Treaty of Versailles imposed harsh terms on Germany which crippled its economy and paved the way for Hitler's rise. 3) By 1939, Germany and the Soviet Union had signed the Nonaggression Pact, alarming other nations, while Germany had begun taking territories like Austria and Czechoslovakia. 4) Most countries did not want another war but were concerned by the expansion of communism and aggression of nations like Germany and Japan.