Opinion: U.S. leaders knew we didn’t have to drop atomic bombs on Japan to win the war. We did it anyway

At a time when Americans are reassessing so many painful aspects of our nation’s past, it is an opportune moment to have an honest national conversation about our use of nuclear weapons on Japanese cities in August 1945. The fateful decision to inaugurate the nuclear age fundamentally changed the course of modern history, and it continues to threaten our survival. As the Bulletin of the Atomic Scientists’ Doomsday Clock warns us, the world is now closer to nuclear annihilation than at any time since 1947.

The accepted wisdom in the United States for the last 75 years has been that dropping the bombs on Hiroshima on Aug. 6, 1945, and on Nagasaki three days later was the only way to end the World War II without an invasion that would have cost hundreds of thousands of American and perhaps millions of Japanese lives. Not only did the bombs end the war, the logic goes, they did so in the most humane way possible.

However, the overwhelming historical evidence from American and Japanese archives indicates that Japan would have surrendered that August, even if atomic bombs had not been used — and documents prove that President Truman and his closest advisors knew it.

The allied demand for unconditional surrender led the Japanese to fear that the emperor, who many considered a deity, would be tried as a war criminal and executed. A study by Gen. Douglas MacArthur’s Southwest Pacific Command compared the emperor’s execution to “the crucifixion of Christ to us.�

“Unconditional Surrender is the only obstacle to peace,� Foreign Minister Shigenori Togo wired Ambassador Naotake Sato, who was in Moscow on July 12, 1945, trying to enlist the Soviet Union to mediate acceptable surrender terms on Japan’s behalf.

But the Soviet Union’s entry into the war on Aug. 8 changed everything for Japan’s leaders, who privately acknowledged the need to surrender promptly.

Allied intelligence had been reporting for months that Soviet entry would force the Japanese to capitulate. As early as April 11, 1945, the Joint Chiefs of Staff’s Joint Intelligence Staff had predicted: “If at any time the USSR should enter the war, all Japanese will realize that absolute defeat is inevitable.�

Truman knew that the Japanese were searching for a way to end the war; he had referred to Togo’s intercepted July 12 cable as the “telegram from the Jap emperor asking for peace.�

Truman also knew that the Soviet invasion would knock Japan out of the war. At the summit in Potsdam, Germany, on July 17, following Stalin’s assurance that the Soviets were coming in on schedule, Truman wrote in his diary, “He’ll be in the Jap War on August 15. Fini Japs when that comes about.� The next day, he assured his wife, “We’ll end the war a year sooner now, and think of the kids who won’t be killed!�

The Soviets invaded Japanese-held Manchuria at midnight on Aug. 8 and quickly destroyed the vaunted Kwantung Army. As predicted, the attack traumatized Japan’s leaders. They could not fight a two-front war, and the threat of a communist takeover of Japanese territory was their worst nightmare.

Prime Minister Kantaro Suzuki explained on Aug. 13 that Japan had to surrender quickly because “the Soviet Union will take not only Manchuria, Korea, Karafuto, but also Hokkaido. This would destroy the foundation of Japan. We must end the war when we can deal with the United States.�

While a majority of Americans may not be familiar with this history, the National Museum of the U.S. Navy in Washington, D.C., states unambiguously on a plaque with its atomic bomb exhibit: “The vast destruction wreaked by the bombings of Hiroshima and Nagasaki and the loss of 135,000 people made little impact on the Japanese military. However, the Soviet invasion of Manchuria … changed their minds.� But online the wording has been modified to put the atomic bombings in a more positive light — once again showing how myths can overwhelm historical evidence.

Seven of the United States’ eight five-star Army and Navy officers in 1945 agreed with the Navy’s vitriolic assessment. Generals Dwight Eisenhower, Douglas MacArthur and Henry “Hap� Arnold and Admirals William Leahy, Chester Nimitz, Ernest King, and William Halsey are on record stating that the atomic bombs were either militarily unnecessary, morally reprehensible, or both.

No one was more impassioned in his condemnation than Leahy, Truman’s chief of staff. He wrote in his memoir “that the use of this barbarous weapon at Hiroshima and Nagasaki was of no material assistance in our war against Japan. The Japanese were already defeated and ready to surrender …. In being the first to use it we had adopted an ethical standard common to the barbarians of the Dark Ages.�

MacArthur thought the use of atomic bombs was inexcusable. He later wrote to former President Hoover that if Truman had followed Hoover’s “wise and statesmanlike� advice to modify its surrender terms and tell the Japanese they could keep their emperor, “the Japanese would have accepted it and gladly I have no doubt.�

Before the bombings, Eisenhower had urged at Potsdam, “the Japanese were ready to surrender and it wasn’t necessary to hit them with that awful thing.�

The evidence shows he was right, and the advancing Doomsday Clock is a reminder that the violent inauguration of the nuclear age has yet to be confined to the past.

Gar Alperovitz, author of “The Decision to Use the Atomic Bomb,� is a principal of the Democracy Collaborative and a former fellow of King’s College, Cambridge. Martin J. Sherwin is a professor of history at George Mason University and author of the forthcoming “Gambling With Armageddon: Nuclear Roulette From Hiroshima to the Cuban Missile Crisis.� Historians Kai Bird and Peter Kuznick contributed to this article.