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Why did Japan attack the United States Pacific fleet and start a war it could not win?

At 0600 on the morning of Dec. 7, 1941, Lieutenant Mitsuo Matsuzaki lifted off in his Nakajima B5N2 torpedo bomber from Akagi, one of six Japanese aircraft carriers sailing in loose formation some 230 miles north of Hawaii. Just under two hours later the man sitting behind Matsuzaki, Commander Mitsuo Fujita, slid back his section of the plane’s canopy and fired a green flare—a signal to the 182 other aircraft of the first assault wave to begin Japan’s surprise attack on the U.S. Pacific Fleet at Pearl Harbor. The flare also marked the start of a war Japan had no hope of winning. The 1941–45 war between Japan and the United States seems, in retrospect, inevitable.

By 1941 Japan, which had subdued much of China, was determined to conquer all of East Asia, including mineral-rich, Western-colonized Southeast Asia. Japan’s imperial ambitions in East Asia inexorably collided with Western interests in the region, and Japan’s 1940 military alliance with Nazi Germany, though of little operational significance, further alienated the Western powers. The United States was preoccupied with events in Europe, especially Britain’s survival, which depended significantly on continued access to imperial manpower and other resources worldwide. But Washington was not prepared to accept Southeast Asia’s subjugation by Japan. Certainly any Japanese attack in the region that included an invasion of the Philippines would mean war. The islands were a strategic liability, but they were still an American colony garrisoned by U.S. military forces.

The Pacific War arose out of Japan’s quest for national glory and economic security via the conquest of Southeast Asia. It also arose out of the Franklin D. Roosevelt administration’s belief that it could check Japan’s bid for an Asian empire through economic sanctions, U.S. force redeployments in the Pacific and other measures short of war. The Japanese sought to free themselves from what they saw as a humiliating economic dependence on the United States, including an almost total addiction to imported American oil, whereas the United States sought to exploit that dependence to thwart Japanese imperial ambitions. The Japanese sought to overturn the territorial status quo in Asia, whereas the United States sought to preserve it. Unless the Western powers had voluntarily abandoned their own empires in Southeast Asia, it is difficult to imagine how Japan could have fulfilled its imperial aims in the region without war.

Despite these facts, Japan’s decision to go to war with the United States continues to perplex. How, in mid- 1941, when the decision was made, could that nation —already militarily bogged down in a four-year war in China and contemplating an attack on the Soviet Union— even think about yet another war, this one against a distant country with overwhelming industrial superiority? The United States was not only much stronger but also lay beyond Japan’s military reach. The United States could (and did) outproduce Japan in every category of armaments, and although Japan could fight a war in East Asia and the western Pacific, it could not threaten the American homeland. In attacking Pearl Harbor and the Philippines, Japan elected to fight a geographically limited war against an enemy who, once fully mobilized, was capable of ultimately waging a total war against the Japanese Home Islands. If the Pacific War was inevitable, was not Japan’s crushing defeat as well? If so, then why did Japan start a war that, as British strategist Colin Gray has argued, it “was always going to lose”?

A common answer, especially among students of the realist school of international relations—which focuses on cold-blooded calculations of power and interest as the primary drivers of state behavior—is that Japanese decision makers in 1941 were simply irrational, even crazy. French political theorist Raymond Aron, for example, believed that Japan’s decision for war “was senseless” because Japan “had no chance of winning and could avoid losing only if the Americans were too lazy or cowardly to conquer.” Gordon Prange, the great historian of Pearl Harbor, called the attack the beginning of “a reckless war [Japan] could not possibly win.” And Roberta Wohlstetter, in her groundbreaking Pearl Harbor: Warning and Decision, denounced the fanciful Japanese thinking behind the decision for war: “Most unreal was their assumption that the United States, with 10 times the military potential and a reputation for waging war until unconditional surrender, would after a short struggle simply accept the annihilation of a considerable part of its air and naval forces and the whole of its power in the Far East.”

Japan’s decision for war against the United States in 1941 was, in fact, dictated by a combination of national pride and the threatened economic destruction of Japan by the United States. Realists tend to dismiss the role of ideas and emotion in interstate relations. In 1941 the Japanese believed themselves a divine race destined to rule Asia. They were a proud people determined to emulate Great Britain and America as great imperial powers. They also resented their profound trade dependence on a United States increasingly hostile to Japanese ambitions in East Asia. Japan’s war machine was vitally dependent not only on American oil, which supplied 80 percent of Japan’s total consumption, but also on imports of U.S. copper, aluminum, zinc, nickel, potash, scrap iron, steel and machine tools. The Roosevelt administration’s growing attempts to use Japan’s trade dependency as a tool of coercive diplomacy only encouraged Tokyo to find another source of economic security.

Decisions involve choice between at least two alternatives, and the alternatives Japan faced in its relationship with the United States in mid-1941 were few and grim: economic ruin, capitulation to a U.S. diplomatic diktat that Japan quit China, or the initiation of war with a much more powerful and strategically invulnerable enemy. The decision for war, disastrous though it was, thus becomes comprehensible. Stanford University political scientist Scott Sagan rightly argues that the “persistent theme of Japanese irrationality is highly misleading, for, using the common standard in the literature (a conscious calculation to maximize utility based on a consistent value system), the Japanese decision for war appears to have been rational.” Sagan further asserts that on close examination of the decisions made in Tokyo in 1941, “one finds not a thoughtless rush to national suicide, but rather a prolonged, agonizing debate between two repugnant alternatives.”

The attack on Pearl Harbor, essentially a flanking raid to shield Japan’s invasion of Malaya, Singapore, the Dutch East Indies and the Philippines, capped a decade of deteriorating U.S.-Japanese relations. Those relations foundered in the 1920s and 1930s on numerous shoals as Japan moved toward dictatorship and war after a decade of flirtation with democracy and internationalism.

The contentious issues driving an ever-larger wedge between Tokyo and Washington included American racism; immigration policies that discriminated against Japanese; accelerated naval competition in the Pacific; U.S. nonrecognition of Japan’s 1931–32 conquest of Manchuria; Japan’s continued aggression in China (and U.S. support for the Nationalist government of Chiang Kai-shek); Tokyo’s military alliance with Adolf Hitler; Japan’s evident imperial ambitions in Southeast Asia; and, beginning in January 1940, escalating U.S. economic sanctions against Japan.

What really brought matters to a head, however, was the combination, in July 1941, of three key events. First, Emperor Hirohito’s July 2 formal authorization of the Japanese military’s planned invasion of Southeast Asia (of which Roosevelt learned just six days later through decrypted intercepts of Japanese diplomatic code traffic between Tokyo and Berlin). Second, Japan’s July 21 occupation of southern French Indochina. And third, the Roosevelt administration’s July 26 freezing of Japanese assets in the United States, which effectively eliminated remaining U.S.-Japanese trade, including Japanese imports of vital U.S. oil. The administration also escalated its diplomatic demands on Tokyo. As the price for restored American trade, the United States now demanded Japan terminate its alliance with Nazi Germany and evacuate not just French Indochina but China itself.

The asset freeze eliminated between 50 and 75 percent of Japan’s foreign trade and left the Japanese little choice but to invade Southeast Asia, as the oil-rich Dutch East Indies (modern-day Indonesia) was the only available substitute for embargoed American oil that lay within Japan’s military reach. But Japan’s vision of empire dictated the expulsion of all Western power and influence from the region, especially that of the hated United States and Great Britain. The Japanese regarded the two Anglo-American powers as strategically inseparable, which meant that an attack on one required an attack on the other, which in turn meant an attack on British colonies and the American-held Philippines.

Initial Japanese plans called for an invasion of the Philippines (whose garrison Roosevelt had hastily reinforced), but not an attack on the U.S. Pacific Feet at Pearl Harbor. It was Admiral Isoroku Yamamoto, commander of Japan’s Combined Fleet, who insisted on including Pearl Harbor, arguing that it would be dangerous to leave the bulk of U.S. naval power in the Pacific intact along the left flank of Japanese forces advancing into Southeast Asia. Yamamoto’s opinion prevailed.

The alternative—diplomatic capitulation to the United States—was far more repugnant than war itself. The Japanese had spent half a century building an empire in East Asia and had invested enormous resources in their stalemated war in China. Moreover, by mid-1941 most Japanese leaders had come to regard war with the United States as inevitable, and none were prepared to give up Japan’s hard-won gains in China for the sake of restored trade with the United States. Certainly none were prepared to accept the four principles of behavior upon which the Americans insisted as the basis for further negotiation: respect for the territorial integrity of all nations, noninterference in the affairs of other countries, equality of commercial opportunity and nondisturbance of the status quo in the Pacific except by peaceful means. The United States was essentially demanding the Japanese renounce what they themselves believed to be their divine destiny in Asia.

The Japanese empire was not going to dissolve itself simply to placate American diplomacy. “No government, least of all the Japanese, could be expected to swallow such humiliating conditions and utter loss of face,” observed noted military historian Sir Basil Henry Liddell Hart in retrospect. The Japanese regarded the U.S. oil embargo as an act of war and would not surrender without a fight. In September 1941 Admiral Osami Nagano, chief of staff of the Imperial Japanese Navy, summed up the Japanese view: “Since Japan is unavoidably facing national ruin whether it decides to fight or not, it must by all means choose to fight. Japan would rather go down fighting than ignobly surrender without a struggle, because surrender would spell spiritual as well as physical ruin for the nation and its destiny.”

In deciding for war against a materially superior United States, did Japan have a theory of victory, or at least of defeat avoidance?

The Japanese recognized they were not strong enough to threaten the American homeland, but the war would be fought in East Asia and the Pacific, which the Japanese controlled or would soon control (after Tokyo’s conquest of Southeast Asia). By fortifying the island chains of the Central and Southwest Pacific, the Japanese believed they could force the United States into a murderous, island-by-island slog that would eventually exhaust America’s will to fight on to total victory. After all, the Roosevelt administration clearly regarded Japan as a lesser threat than Nazi Germany, and the strength of U.S. interests in East Asia could never equal Japan’s.

In his book Choices Under Fire historian Michael Bess summarized the reasoning behind Japan’s strategy: “[The Americans] can come and fight us to liberate those territories, or they can accept the fact that the map of Asia has been redrawn, and that they must henceforth learn to deal with a Japanese-led Asian bloc. If we make it clear that kicking us Japanese out of our new Asian empire is going to require a long, bloody fight, then there is a good chance that the Americans will regard the battle as simply not being worth the high cost in lives. Controlling the southwestern Pacific is not a vital interest of the United States.” As it turned out, the Japanese were correct in assuming they could impose a protracted war of attrition on the Americans, but they were fatally mistaken in believing that such a war would sap American will to pay the necessary price for subjugating Japan.

Underlying the Japanese hope they could bleed the Americans into a political settlement short of total victory—a belief that persisted among Japan’s military leadership well into 1945—was a confidence that Japanese racial and spiritual superiority could neutralize U.S. material superiority. Japan was neither the first nor the last of America’s enemies to stress the superiority of the human element in war and to underestimate the resolve of Americans in war.

The Japanese were fully aware of their comparative industrial weakness (Yamamoto had spent much time in America and was very pessimistic about Japan’s chances in a long war with the United States), but they had long believed that the unique qualities of their race—including a superior national will, discipline and war-fighting prowess—could defeat the strong but soft Americans. Joseph Grew, the prewar U.S. ambassador to Japan, testified after the war, “The Japanese regarded us as a decadent nation in which pacifism and isolationism practically ruled the policy of our government.”

Moreover, as British historian H.P. Willmott points out, in 1941 Japan was “a nation with no experience of defeat and, more importantly, a nation created by and watched over by the gods and ruled by a god. …This religious dimension provided the basis for the belief in the superiority of the Japanese martial commitment —Yamato damashii—that was the guarantee against national defeat.” Many Japanese shared the view of Rear Admiral Tasuku Nakazawa, chief of the Imperial Japanese Navy operations section, that America was “a composite nation of immigrants, lacked unity, could not withstand adversity and privations, and regarded war as a form of sport, so that if we deal a severe blow at the outset of hostilities, they would lose the will to fight.”

As a creature-comforted, racially impure and capitalist society, America was, in Japan’s view, simply too soft to sustain the blood-and-treasure costs of a long, harsh war, especially in a region—East Asia—where the strength of U.S. interests was weak relative to the strength of Japanese interests, and at some point the capitalists who controlled the United States would turn against a war whose balance sheet was registering far more costs than benefits. “The [Japanese] military went into the Pacific War still clinging to the concept of fighting spirit as decisive in battle,” observed Japanese historian Saburo Ienaga. “The result was a wanton waste of Japanese lives, particularly in combat with Allied forces whose doctrine was based on scientific rationality.” Indeed, absent Japanese racial stereotyping of America as a nation of self-indulgent couch potatoes incapable of heroic sacrifice, Japanese war plans made little sense, as Tokyo did clearly recognize the great American advantage in materiel strength. Japanese quality had to offset U.S. quantity.

The Japanese were oblivious to the likely political and psychological effects of their surprise attack on Pearl Harbor. Far from increasing American political disharmony, the Sunday-morning “sneak attack” enraged all Americans, regardless of class, color or partisan persuasion, and in one fell swoop demolished isolationism as both a potent political force in U.S. politics and a brake on Roosevelt’s interventionist foreign policy. By galvanizing public opinion behind total war against Japan, Pearl Harbor also virtually guaranteed Japan’s eventual and utter destruction. No amount of damage the Japanese might have inflicted on the U.S. Pacific Fleet in Hawaii (unluckily for the Japanese, the fleet’s three aircraft carriers were absent from Pearl Harbor on Dec. 7, 1941) could make good the decision to attack in the first place.

Pearl Harbor’s catastrophic strategic consequences for Japan raise one of the great counterfactual questions of World War II: What if the Japanese had confined their invasion of Southeast Asia only to British- and Dutch-controlled territory? The Philippines had little to offer Japan in the way of desired natural resources, and until Dec. 7, 1941, Roosevelt was in no political position to commit the United States to the defense of Malaya, Singapore and the Dutch East Indies or any other European colony in the region. Could he, absent a Japanese attack on American territory somewhere in East Asia or the Pacific, have asked for, much less obtained, a declaration of war from a Congress (especially the Senate) still heavily populated by isolationists? Had the Japanese chosen invasion of Southeast Asia and not war with the United States, how might the course, even outcome, of World War II have been altered? Presidential aide and confidante Harry Hopkins recalled several talks with Roosevelt in the year leading up to Pearl Harbor in which Roosevelt expressed concern that “the tactics of the Japanese would be to avoid conflict with us.” He also recalled the president’s subsequent “relief” that the Japanese did indeed attack U.S. territory on December 7 because “it completely solidified the American people.”

In the end, the judgment of the U.S. Army’s official history of the Pacific War still stands:

Perhaps the major error of the Japanese was their decision to attack the United States when the main objective of the war was to gain the strategic resources of Southeast Asia. Had they bypassed the Philippines and rejected Yamamoto’s plan for the strike against Pearl Harbor, it is possible that the United States might not have gone to war, or, if it had, that the American people would have been more favorably disposed toward a negotiated peace. While the Japanese would have had to accept certain risks in following such a course, they would not have forced the United States to declare war.


For further reading Jeffrey Record recommends Edward S. Miller’s Bankrupting the Enemy: The U.S. Financial Siege of Japan Before Pearl Harbor, and A Gathering Darkness: The Coming of War to the Far East and the Pacific, 1921–1942, by Haruo Tohmatsu and H.P. Wilmott.

Originally published in the January 2012 issue of Military History. To subscribe, click here.