French Indochina and a stronger Far East deterrent

Free French control of Indochina means Japan would have to conquer Vietnam instead of obtaining it through pressure on Vichy authorities. An attack on Malaya or Singapore would then begin from farther back, and a Southeast Asian war might open with an invasion of Vietnam. That additional campaign would buy time for the Allies, while leaving an attack on Hawaii possible. French and British submarines and other ships could remain in the Far East because fewer had been withdrawn to the Mediterranean. Richelieu might also be completed in Britain or America and join the Allied battle line, although the timing is uncertain. The stronger Allied position would change Japan's military calculations without establishing whether it would prevent war.