How much oil security did Japan have in 1939?

How dependent was Japan on American oil, and how much fuel had it stockpiled by early 1939?

Japan still obtained most of its oil from the United States and had little accumulated reserve after major operations in China, while continued fighting also consumed fuel and resources.

The economic vulnerability is greater than a reader familiar with late 1941 might expect. Japan still relies heavily on American oil and has not had the later embargo period in which to organize its response or seize southern resource areas. Its forces have recently conducted major operations in China and continue to face conflict there and on the Soviet frontier, so fuel is already being consumed. An embargo or effective maritime blockade would therefore begin constricting Japanese operations before the navy had built a comfortable strategic reserve.