Answer: After the Japanese invasion of China and the French Indochina, the United States began to restrict trade with Japan. The U.S. ceased exporting planes, airplane parts, aviation fuel, machine tools, and oil. Due to the lack of resources Japan was now receiving, they were in desparate need of rubber and oil. Japan had been warned by President Roosevelt about attacking any other SouthEast Asian countries. Since negotiations with the U.S. had been unsuccessful, and with no other alternatives left, Japan decided to attack Pearl Harbor. Their hope was that if the blow was devastating enough, it would discourage the U.S. from entering the war.