Imminence and the Pearl Harbor Dilemma

 “When you see a rattlesnake poised to strike, you do not wait until he has struck before you crush him.”  —Franklin D. Roosevelt, September 11, 1941

On November 26, 1941, a Japanese carrier force slipped out of port and headed east across the Pacific under strict orders to attack the U.S. Navy fleet at Pearl Harbor. We know how that turned out, but suppose the United States had learned that the Japanese fleet had sailed and had intelligence that disclosed its mission before the Japanese struck on December 7. Would Washington have been justified in hitting them first? In hindsight, the answer is yes, but what about when that question mattered most: before the attack?

More than a century earlier, a similar question helped shape the principle of self-defense in international law.

In 1837, British forces crossed into American territory and destroyed the American steamer Caroline, which had been supplying Canadian rebels. The incident—known as the Caroline Affair—created a diplomatic dispute between the United States and Britain. In defending the American position, Secretary of State Daniel Webster argued that pre-emptive self-defense could be justified only when the necessity was “instant, overwhelming, leaving no choice of means and no moment for deliberation.” He asserted that Britain's actions failed to live up to that standard.

Using Webster's criteria, what would Congress have done if it had become aware of the reason behind the movement of the Japanese fleet on November 26, 1941? Would they have declared war on Japan? They had the authority to, even without a request from President Roosevelt. Or would the partisans and isolationists have defeated such an effort? What evidence might the President have been required to present to Congress to move enough partisans and isolationists to agree that Japanese intentions were hostile and that the danger was immediate?

Could he have convinced them that an attack was imminent? And what exactly does “imminent” mean? Does it mean today? Tomorrow? Or does it mean that the “moment for deliberation”—negotiations—had been attempted and exhausted and that offensive action was the only acceptable recourse?

Congressional debate likely would have centered on precisely that question. A fleet sailing from port isn’t proof of a plan to attack. The Japanese were involved in several operations across the Pacific in 1941. Who’s to say that the Japanese fleet was headed to Hawaii rather than for British Malaya, the Dutch East Indies, or the Philippines. No shots had been fired, and no American territory had been attacked.

Congress might have even warned President Roosevelt against taking action against the Japanese fleet because doing so would amount to starting a war. The America First Committee had already claimed that the U.S. was provoking conflict with Japan and Germany when the U.S. imposed an oil embargo against Japan, provided military assistance to Britain and China, and conducted naval patrols in the Atlantic against German submarines. A pre-emptive attack on the Japanese fleet would have seemed to confirm their claim that Roosevelt was itching to drag the country into war, perhaps even by starting one himself.

Congress might have invoked a measure similar to one raised a century earlier by freshman congressman Abraham Lincoln.

In May 1846, President Polk asked Congress to acknowledge that Mexico had begun hostilities when fighting broke out between American and Mexican troops north of the Rio Grande River. Congress responded with a declaration of war. But some members of Congress believed Polk himself had provoked the fighting by sending troops into disputed territory. Lincoln proposed what became known as the Spot Resolutions, demanding that the President identify the precise spot where American blood had been shed and prove that it had been shed on American soil, as Polk had claimed. The implication behind the resolutions was that if the fighting happened in disputed territory, it might have been Polk—not Mexico—who started the war and that Polk had requested the declaration under false pretenses.

The resolutions ultimately failed to pass. Congressional leadership was reluctant to approve a resolution that would undermine troops in the field, particularly since the war had the support of the American people.

So, what to do about the Japanese fleet? And what about public opinion? A large segment of the American population was still war-weary from World War I—“the war to end all wars.” A pre-emptive—or preventative—attack on the Japanese might have divided the country, with many Americans concluding that the United States had made an unprovoked attack.

The final argument might have been that in late November 1941, even as the Japanese fleet was underway, American and Japanese diplomats were still negotiating in Washington over Japan’s war in China, U.S. economic sanctions, the U.S. oil embargo, and Japanese aggression in Southeast Asia. As long as negotiations continued, the United States could reasonably assume that it remained in Webster's "moment for deliberation." The problem was that while Washington believed deliberation was still underway, Tokyo had already moved beyond it. By the time American leaders realized that negotiations had failed and that an attack was "imminent," it was too late.

Despite that, and despite the likelihood that a pre-emptive strike would have divided the country, if the American people later learned that U.S. intelligence had discovered Japanese intentions before the attack but failed to stop it, the question for the President and Congress afterward would have been "why?"

Still, before the attack, it's far from certain that Congress—or the nation—would have agreed that the danger was imminent, even if they had known that the Japanese fleet had sailed. As it was, the only real proof came after the fact, and at a terrible cost: the loss of the U.S. battleships in port, the degradation of the Pacific Fleet, the destruction of aircraft and key U.S. naval and military bases, and the loss of 2,400 American lives.

As difficult as this dilemma would have been in 1941 under the Webster standard, the pace of warfare, the rapidly changing nature of battlefield technology, and the capabilities of the global terrorist threat would make it even more imposing today. Where we once set our sights on anticipating and stopping attacks when they became imminent, we must now infer and prevent future attacks before our ability to stop them becomes impossible.