You're simply changing the goalposts. First you start off with saying that the oil embargo was casus belli since the US <demanded unconditional withdrawal from

You're simply changing the goalposts. First you start off with saying that the oil embargo was casus belli since the US <demanded unconditional withdrawal from China.> This is factually incorrect. The goal of the oil embargo was to get Japan out of Indochina, not China or Manchuria. Japan could have finessed this by installing a puppet regime (ala Manchuko), but their arrogance wouldn't allow that. Now you move from <a general deciding to attack Perl(sic) Harbor is making the best and most rational decision> to <an admiral who's not in a senior role has in the Empire of Japan> Yamato is the architect of both the tactical plan of attacking Pearl Harbor, as well as the strategy of reducing American seapower (by attacking PH) and then defeating them in a decisive battle (Midway). He's not some lower ranking officer, he's the intellectual and martial spirit of the IJN. This also shows a fundamental misunderstanding of the power and influence of Yamamoto. Yamamoto was the most powerful officer in the IJN, and also had tremendous influence with the Imperial Family. Yamamoto could have used this influence earlier, to moderate Tojo's ambitions, and to avoid conflict with the US. He knew that Japan could never defeat the US over time, but still acted irrationally in a way that failed Japan. You're also confused about the timing of the oil embargo, and the Hull note. The oil embargo (along with other trade restrictions and confiscation of Japanese assets) began immediately in July 41 after the Japanese began to make obvious preparations to attack either the British in Malaya, or the Dutch in the East Indies. The Hull note was a last ditch attempt in late November to forestall war. At this point, war was inevitable; the attack on Pearl Harbor had been planned since Spring of 41, and the Kido Butai had already departed before the Hull note was sent.