An embargo is placed on Japan by the United States, depriving her of much needed natural resources to carry on her war with China.
Prior to the December 7, 1941, bombing of Pearl Harbor, Oahu in the Hawaii Islands by Japan, that country had signed a Pact with Germany and Italy. Not only was the pact designed to expand Japan's industry but to allow Japan to carry on its ongoing assault on China for another three years.
This was the start of Japan's "special undeclared war with China." Shortly afterwards, on July 7, 1937, Chinese and Japanese forces clashed outside of Peking. This Japanese encroachment on China had been taking place long before 1936.
Basically, Japan, in order to expand her industry, need China's natural resources. By 1939, Europe's own move toward war all but halted Japan receiving any natural resources from that factor. Not only that, but also by this time Japan was going broke as her ongoing conflict with China was costing her some $5,000,000 a day.
In 1940, as events heated up in Europe, the commercial treaty governing trade relations between the United States and Japan lapsed. From that time on, in Congress there were demands for a "total trade embargo against Japan." The result was that Japan was deprived of aviation fuel, scrap metal, and eventually copper and brass, then virtually every raw material of importance from America.
Needless to say this did not make the Japanese happy campers or look upon the United States with kindness because on July 21, 1941, the Japanese government "formally declared" that it was in favor of war with the United States of America.
Bombing Pearl Harbor: A Day of Infamy continues with Prelude to War: Japan Negotiates and Prepares for Attack.
Previous: Bombing Pearl Harbor: A Day of Infamy.
After the Bay of Pigs: Placing the Blame.
Before the Cuban Missile Crisis: Who Has the Biggest Gun?