Was Yamamoto Rational?

In the months and years prior to the Japanese attack on Pearl Harbor, the American military was very aware of the potential danger that the Japanese navy posed to the harbor and to the ships based there. As early as 1933, joint Army-Navy maneuvers were predicated on a Japanese attack on Pearl Harbor; and by early 1941, as tensions with Japan mounted, Lieutenant General Walter Short, commander of Army forces in Hawaii and responsible for the physical security of Pearl Harbor and of the US Pacific Fleet when it was present there, and Husband Kimmel, commander-in-chief of the US Pacific Fleet understood that Pearl Harbor could very well be on the Japanese navy's list of targets if war came. Short especially was acutely aware of the difficult position that a defender of Pearl Harbor was in. There weren't enough long-range reconnaissance planes to conduct continuous 360-degree patrolling to alert Pearl Harbor's defenders of an enemy attack before it struck, and early warning was essential to all of the defense plans that he and Kimmel had. And yet the Japanese took Kimmel, Short, and just about everybody else in the US military establishment by surprise when they struck on December 7. Why? I'm sure that there are a number of reasons for this, but one of them had to have been the deep-seated conviction by most members of the US Army and Navy that the Japanese had the initiative or the ingenuity to pull such an attack off and that, even if they did, they never would because doing so would be irrational: a war with the United States made no sense because the industrial capacity of the United States was so much larger than that of Japan. The United States was destined to win any protracted conflict.

To be honest, I don't know how widespread this attitude is in current historical literature; but it is something that I have read and heard before. However tactically brilliant the attack on Pearl Harbor was, it was a strategic disaster that ultimately spelled the destruction of imperial Japan. Well, I don't think that this argument is persuasive. Consider the position that Japan found itself in at the end of 1941. The United States had cut off its supply of oil and scrap metal in response to Japanese aggression in China, and the Japanese war machine relied on those raw materials. The embargo placed Japan in a very tough position: either they could forswear their imperial ambitions in China and elsewhere in Asia, or they would have to find another source of oil and iron. Realistically speaking, getting oil meant invading the Dutch East Indies and other territories in the Southwest Pacific. That would mean war with the United States. So the choice was either to give up or go to war with the United States. There was no way that the Japanese of the ruling classes would have given up, so that implied war. Isoroku Yamamoto, the commander-in-chief of the Japanese Combined Fleet and the guiding light of the attack on Pearl Harbor, may not have wanted war with the United States; but he absolutely wanted to maximize his country's chances of winning it if it came. He knew that the US almost certainly would win a protracted conflict, but an attack that crippled the US Pacific Fleet would allow the Japanese to take control of the Southwest Pacific and put them in a better position to resist the inevitable American counterattack. The more difficult that counterattack was, the more likely it was that eventually the US would give up and leave the Japanese to their new territory. Destroying the US Pacific Fleet gave the Japanese the best chance to win a war with the US, and from their perspective, they had to fight the US or be humiliated. That the attack did not allow the Japanese ultimately to succeed does not means that it was irrational or ill-considered. (Which is not to say, of course, that it was not still perfidious.)