Japanese wanted to stop all aids received by china from the allied countries and United States.
Step-by-step explanation:
United States was indulging in trade with China along with England, Russia. By this time there was Syno Japanese’s war before Europe declared war on China. In Syno-Japanese war, Japan captured five north provinces of China and Manchuria. Japanese wanted to restrict all aid and assistance received by China from United States and other allied powers. This request was turned down and United States placed an embargo on Japan.
Japan got annoyed due to this trade restriction by United States because japan relied much on trade relationship with US especially for steel imports in order to make weapons and ammunition. Hence Japan retaliated by claiming an assault on Pearl Harbor in US.