The oil embargo had much more to do with Japan marching into French Indochina. Like you said, Japan invaded Manchuria in 1931, and the US took no action. In 193

The oil embargo had much more to do with Japan marching into French Indochina. Like you said, Japan invaded Manchuria in 1931, and the US took no action. In 1937, Japan starts invading the rest of China after the Marco Polo bridge incident, and the US still did nothing even after Japanese bombers hit the USS Panay on the Yangtze river. December 1937, Nanjing Massacre, again no direct action from the US. (But plenty of funding to the ROC and supplies being shipped into China through French Indochina, part of the reason why Japan would later occupy this area) The US didn't start limiting oil and scrap iron shipments to Japan until 1940, after supplying a decade of Japanese military adventures. Why 1940? In 1940, Nazi Germany defeats France and the Vichy French government allows Japan to occupy French Indochina. Suddenly, Japan controls the world's main source of rubber, is within striking distance of the Dutch East Indies and its oil supply which the UK needs to hold out against Germany, and has occupied a western colony.