ANY appraisal of what happened and why at Pearl Harbor must begin by asking: did President Roosevelt know? Were he and his lieutenants aware that a Japanese attack was coming, and did they, eager to drag the United States into war, withhold information from the commanders in Hawaii?The answer is no - on both counts. Yes, the Army had broken certain Japanese codes. Yes, Japan was enraged by the American oil embargo and was talking tough. But the codes broken were diplomatic not military, and the Japanese ships kept radio silence. Americans, seemingly safe behind two oceans, knew nothing of surprise attack. Nor was the government organized for rapid response. MacArthur's bombers in the Philippines, for example, were destroyed nearly 10 hours after news arrived of Pearl Harbor. National security revolved around busy, worried officials who, anxious about Hitler's war machine, hardly heard the snarls from Tokyo. Those snarls did not necessarily point to Pearl Harbor. Why should Japan risk its precious carriers by attacking this fortress? Might not Japan lunge at Thailand, just as it had at Indochina? That would threaten both Singapore and the Burma Road, but Roosevelt hardly dared counter this indirect assault on a British Empire detested by many Americans. And neither he nor anyone else took Japan seriously enough to really fear a Pacific showdown. Japan was perceived as ambitious but essentially inferior, lacking economic depth. Its warships were thought to be easily capsized (one had in 1934), its paper cities vulnerable to fire-bombing, and its Army was discounted as incapable of conquering even a weak China. Surely Japan would not commit suicide by attacking the two most powerful countries on earth? Not for the last time, American leaders were underestimating an Asian adversary. What Roosevelt did focus on was joining Britain and Russia in defeating the greatest danger of all: Germany. One enemy at a time was his strategy, and he hoped to provoke an Atlantic naval incident that would bring war with Hitler. Japanese expansion was to be deterred by economic pressure, the fleet at Pearl Harbor, a growing bomber force in the Philippines, and support for China. Once Hitler was defeated, the American and British navies could take on the Japanese militarists, forcing them out of China. But a war with Japan in 1941? Roosevelt and his commanders rejected this affront to strategic common sense. Revisionist historians who argue otherwise, treating the American oil embargo as a sly provocation of a peaceful Japan, ignore the realities of the time. The Japanese were hardly peace-loving. Their militarists had fought one small war after another since 1895. Success brought dreams of an empire. Japan was stuck in the China quagmire. America was blamed: witness the oil embargo. Surely the Chinese would have given in, were it not for American mischiefmaking. The Americans should be taught a lesson, while Hitler kept the West in turmoil. Japanese militarists argued that they had a heaven-sent opportunity to attack, before the hostile ring surrounding Japan tightened. Japan had a superb naval air force under Admiral Yamamoto, an imaginative commander who had uncovered the weaknesses of Pearl Harbor, and who was willing to risk the carriers on a 4,000-mile sortie across the Pacific. The gamble paid off. Surprise was achieved, and Japan - with negligible losses - crippled the American battle line. In reality, however, they lost much more. The rage that swept the US ruled out a negotiated peace. And the battleships shattered at Pearl Harbor handed dominance to the aircraft carrier, which became the cornerstone of US naval power. But Americans lost as well. Overconfidence had brought military disaster, but no serious rethinking of attitudes regarding Asians. American leaders continued to be surprised by the strength of Asian adversaries, surprised by the North Korean attack in 1950, by the Chinese intervention that followed, and especially by the fighting power of Vietnamese communists. Americans learned at Pearl Harbor to be vigilant, but not to think critically about their role in East Asia, where a new political order was comi ng alive, even as the bombs fell at Pearl Harbor.