Roosevelt would probably announce the sighting, and the Japanese carriers would probably withdraw. The uncertainty is whether Tojo orders the retreat, Yamamoto acts first, or imperial intervention removes Tojo after a confrontation. A Tojo-led withdrawal is expected to delay war by only two or three years, while a government change leaves more room for peace. Renewed fuel imports would give Japan time to reorganize and consider how to counter the coming Essex-class carrier fleet. Further I-400 submarine development is one speculative possibility. Delay would also let the larger American industrial base pull farther ahead, so restored fuel supplies would buy Japan options without resolving the underlying imbalance.
Chapter · 1:35:09-1:40:33
The likeliest outcome: withdrawal and a rearmament race
A public warning would probably make the Japanese carriers withdraw, leaving both powers time to rearm and Japan facing a growing industrial disadvantage.