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Why Truman Dropped the Bomb

From the August 8, 2005 issue: Sixty years after Hiroshima, we now have the secret intercepts that shaped his decision.

Aug 8, 2005, Vol. 10, No. 44 • By RICHARD B. FRANK
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The sixtieth anniversary of Hiroshima seems to be shaping up as a subdued affair--though not for any lack of significance. A survey of news editors in 1999 ranked the dropping of the atomic bomb on August 6, 1945, first among the top one hundred stories of the twentieth century. And any thoughtful list of controversies in American history would place it near the top again. It was not always so.
In 1945, an overwhelming majority of Americans regarded as a matter of course that the United States had used atomic bombs to end the Pacific war. They further believed that those bombs had actually ended the war and saved countless lives. This set of beliefs is now sometimes labeled by academic historians the "traditionalist" view. One unkindly dubbed it the "patriotic orthodoxy."

But in the 1960s, what were previously modest and scattered challenges of the decision to use the bombs began to crystallize into a rival canon. The challengers were branded "revisionists," but this is inapt. Any historian who gains possession of significant new evidence has a duty to revise his appreciation of the relevant events. These challengers are better termed critics.

The critics share three fundamental premises. The first is that Japan's situation in 1945 was catastrophically hopeless. The second is that Japan's leaders recognized that fact and were seeking to surrender in the summer of 1945. The third is that thanks to decoded Japanese diplomatic messages, American leaders knew that Japan was about to surrender when they unleashed needless nuclear devastation. The critics divide over what prompted the decision to drop the bombs in spite of the impending surrender, with the most provocative arguments focusing on Washington's desire to intimidate the Kremlin. Among an important stratum of American society--and still more perhaps abroad--the critics' interpretation displaced the traditionalist view.

These rival narratives clashed in a major battle over the exhibition of the Enola Gay, the airplane from which the bomb was dropped on Hiroshima, at the Smithsonian Institution in 1995. That confrontation froze many people's understanding of the competing views. Since then, however, a sheaf of new archival discoveries and publications has expanded our understanding of the events of August 1945. This new evidence requires serious revision of the terms of the debate. What is perhaps the most interesting feature of the new findings is that they make a case President Harry S. Truman deliberately chose not to make publicly in defense of his decision to use the bomb.

When scholars began to examine the archival records in the 1960s, some intuited quite correctly that the accounts of their decision-making that Truman and members of his administration had offered in 1945 were at least incomplete. And if Truman had refused to disclose fully his thinking, these scholars reasoned, it must be because the real basis for his choices would undermine or even delegitimize his decisions. It scarcely seemed plausible to such critics--or to almost anyone else--that there could be any legitimate reason that the U.S. government would have concealed at the time, and would continue to conceal, powerful evidence that supported and explained the president's decisions.

But beginning in the 1970s, we have acquired an array of new evidence from Japan and the United States. By far the most important single body of this new evidence consists of secret radio intelligence material, and what it highlights is the painful dilemma faced by Truman and his administration. In explaining their decisions to the public, they deliberately forfeited their best evidence. They did so because under the stringent security restrictions guarding radio intercepts, recipients of this intelligence up to and including the president were barred from retaining copies of briefing documents, from making any public reference to them whatsoever at the time or in their memoirs, and from retaining any record of what they had seen or what they had concluded from it. With a handful of exceptions, they obeyed these rules, both during the war and thereafter.

Collectively, the missing information is known as The Ultra Secret of World War II (after the title of a breakthrough book by Frederick William Winterbotham published in 1974). Ultra was the name given to what became a vast and enormously efficient Allied radio intelligence organization, which secretly unveiled masses of information for senior policymakers. Careful listening posts snatched copies of millions of cryptograms from the air. Code breakers then extracted the true text. The extent of the effort is staggering. By the summer of 1945, Allied radio intelligence was breaking into a million messages a month from the Japanese Imperial Army alone, and many thousands from the Imperial Navy and Japanese diplomats.