American Embargoes and Japan
Japan relied very heavily on American oils and metals to supply their war efforts in China. Without those exports, their invasion of China would have to be altered drastically. After Japan invaded China, Roosevelt took some action on behalf of China. In May of 1939, the United States notified Japan that it would be withdrawing from the Treaty of Commerce. Shortly after, the United States started imposing embargoes on supplies such as aviation gasoline, oil, tools, iron, steel, copper, bronze, and many other critical metals. With a dwindling supply of petroleum, Japan had to either give up the war with China or secure its own forces. After failed negotiations with the United States, Japan declared war on the U.S.