Political map of East Asia and the Western Pacific 26 September 1940 (Japanese invasion of French Indochina): While Nomonhan (Battles of Khalkhin Gol) and the Molotov-Ribbentrop Pact seemed to put an end to ideas of Japanese expansion north, the outbreak of World War II and the rapid German victories over France and the Netherlands (Fall of France) left the European colonies in southeast Asia vulnerable. Japan was quick to exploit this new opening, landing troops in northern French Indochina (Japanese invasion of French Indochina).