Zengo Yoshida judged the Tripartite Pact partly by Germany's willingness to share coal-to-oil technology and help Japan build synthetic-fuel plants. Japan had coal but lacked oil, so the transfer would address a basic wartime weakness despite its high cost. Yonai and Prince Fushimi also supported building the plants, although Fushimi still favored war in 1941 as a way to seize oil. Leaders who disagreed about going to war could still agree that Japan needed a more secure fuel supply.
Notable Point · 42:03-47:25
Yoshida made synthetic fuel a test of the Tripartite Pact
Fuel technology offered a concrete measure of whether alliance with Germany would improve Japan's ability to sustain a war.