For decades, there has been an argument in the United States every August 6 and 9, the anniversaries of the atomic bombings of Hiroshima and Nagasaki.

One side says the Japanese militarists were brutal and determined to fight to the end; there is substantial evidence for this. The United States captured Saipan and Tinian in the summer of 1944, about a year before Japan surrendered. The critical importance of this event, sometimes called the Pacific D-Day, is evidenced by the fact that Prime Minister (and General) Hideki Tojo, who led Japan to war with the United States after he was appointed to that office in late 1941, resigned right after the American victory in Saipan. The strategic reality was that Japan was now within range of U.S. B-29 bombers. The war could only conclude with a U.S. victory on U.S. terms. (Tinian was the base from which the B-29 bombers that destroyed Hiroshima and Nagasaki took off.) That a U.S. victory was inevitable was devastatingly demonstrated, months before Hiroshima, by the fire bombing of Tokyo on March 10, 1945 with hundreds of B-29 bombers participating in the air raid. Yet Japan did not surrender in late 1944 or in March 1945. Even after the atomic bombings, there remained Japanese military leaders who wanted to fight on. Each August 6 we also hear that the bombings ended the war, thereby saving half a million (or more) American lives thereby obviating the need for an invasion of the Japanese homeland, which would be fiercely defended.

The other “revisionist” side says that atomic bombings were were unjustified because the war was essentially over. By mid-July 1945, the United States had cable traffic in hand indicating a strong Japanese faction in favor of surrender if their emperor was allowed to remain on the throne (the very one who had given the go-ahead for the war, but who, in the end was allowed to remain, but only after the bombs had been used). U.S. generals’ upper estimate of U.S. military deaths in an invasion of Japan was less than 50,000 — a huge number but far smaller than common post-war claims. Who would know better how to estimate casualties than the U.S, military leaders who had been in the thick of the brutal war in the Pacific where the casualty rate was infamously high? (For reference, total U.S. combat deaths in the European and Pacific theaters combined, in World War II were about 300,000; of these, Pacific theater deaths were about 100,000 – though of course, the invasion of Japan was avoided, unlike the European theater, where the fighting went on till Germany was occupied and physically vanquished, with Hitler dead. An additional 100,000 or so died of non-combat causes.) General Groves, who directed the Manhattan Project, said that it was conducted on the basis that “Russia was our enemy.” The bombings were really a message to the Soviets about the shape of the post-war world and who would run it. These assertions also are substantially true.

Yet, the truths expressed by both sides taken together are not large enough to account for a complex reality; much that is essential does not enter either picture. Those who say the bombings ended the war almost never acknowledge the major role that the Soviet declaration of war on Japan on August 8, 1945 played in the Japanese surrender. For them, the bombings did it. Yet, U.S. military leaders and President Truman himself believed that a Soviet declaration of war on Japan would be decisive. Japanese deliberations that led up to the surrender, including on the day of the Nagasaki bombing and just after the Soviet declaration of war on Japan, indicate the centrality of the Soviet entry. The Soviets had already occupied much of Eastern Europe; Japan did not want Soviet occupation. If a choice had to be made, the Japanese would rather surrender to the Americans.

Neither argument takes into account that the purpose of the Manhattan Project was to prevent Hitler and the Nazis from getting a monopoly of the bomb; yet Germany was explicitly de-targeted on May 5, 1943, two years before the end of the war in Europe. Too little attention is paid to the fact that the bomb project was accelerated in December 1944 when there was definitive evidence that Germany did not have a viable bomb project. Only one scientist, Joseph Rotblat, left Los Alamos then. A quarter of a century later, Richard Feynman, one of the many brilliant physicists at Los Alamos who stayed till the end, regretted that he did not reflect that the purpose of the project had been accomplished when Germany was defeated. (“I simply didn’t think, okay?” he said.)

Then there is the fact of the timing of the use of the bombs. The Allies, including the Soviets, had agreed in July 1945 that the Soviet Union would declare war on Japan on August 15, 1945. (The Soviets accelerated their entry by a week after the bombing of Hiroshima.) The invasion of Japan was not due to start until November 1, 1945. Moreover, U.S. military leaders knew that the atomic bombings may put the lives of U.S. prisoners of war at risk. So why not wait for a few days to see if the Soviet entry would trigger a surrender? But they did not.

The bombings of Hiroshima and Nagasaki have shaped our world ever since and kept us on the edge of utter catastrophe for decades; they need to be understood on a much larger historical canvas, deserving of such a critical event in human history. That canvas should include the US-Japanese competition in the Pacific at the start of the twentieth century (friendly, or at least accommodating, at first) as the U.S. extended its reach beyond its shores and Japan decided to become an imperialist power in the East, conquering Korea and defeating imperial Russia in the 1905 war; the U.S. decision to re-locate the Pacific fleet to Pearl Harbor from San Diego in 1940 despite the misgivings of naval leaders that it would be a target for Japan; the Japanese bombing of Pearl Harbor; the early atomic targeting of Japanese forces and the de-targeting of Germany in 1943 (in an April 1945 briefing paper for the newly installed President Truman, Groves wrote “The target is and was always expected to be Japan“; italics added); and U.S. post-war aims that started taking shape soon after World War II began in Europe. I tried to bring these aspects together in a speech I gave in Santa Fe in 2012. It was entitled From Pearl Harbor to Hiroshima. Despite the end of the Cold War three decades ago, nuclear dangers are rising. This August, when we again remember the bombings that proclaimed the start of the nuclear age to the world, it might be worth an hour of your time.