Japan and the U.S. engaged in negotiations during the course of 1941 in an effort to improve relations. During these negotiations, Japan considered withdrawal from most of China and Indochina after drawing up peace terms with the Chinese. Japan would also adopt an independent interpretation of the Tripartite Pact, and would not discriminate in trade, provided all other countries reciprocated. However, these compromises in China were rejected by General Tojo, then War Minister. Responding to Japanese occupation of key airfields in Indochina (July 24) following an agreement between Japan and Vichy France, the U.S. froze Japanese assets on July 26, 1941, and on August 1 established an embargo on oil and gasoline exports to Japan. The oil embargo was an especially strong response because oil was Japan 's most crucial import, and more than 80 % of Japan 's oil at the time came from the United States.
why did the us imposed an oil embargo on japan
Japanese occupation of key airfields in Indochina (July 24) following an agreement between Japan and Vichy France