the REAL reason america used atomic weapons against japan

Washingtonsblog | History.com notes:

In the years since the two atomic bombs were dropped on Japan, a number of historians have suggested that the weapons had a two-pronged objective …. It has been suggested that the second objective was to demonstrate the new weapon of mass destruction to the Soviet Union. By August 1945, relations between the Soviet Union and the United States had deteriorated badly. The Potsdam Conference between U.S. President Harry S. Truman, Russian leader Joseph Stalin, and Winston Churchill (before being replaced by Clement Attlee) ended just four days before the bombing of Hiroshima. The meeting was marked by recriminations and suspicion between the Americans and Soviets. Russian armies were occupying most of Eastern Europe. Truman and many of his advisers hoped that the U.S. atomic monopoly might offer diplomatic leverage with the Soviets. In this fashion, the dropping of the atomic bomb on Japan can be seen as the first shot of the Cold War.

New Scientist reported in 2005:

The US decision to drop atomic bombs on Hiroshima and Nagasaki in 1945 was meant to kick-start the Cold War rather than end the Second World War, according to two nuclear historians who say they have new evidence backing the controversial theory.
Causing a fission reaction in several kilograms of uranium and plutonium and killing over 200,000 people 60 years ago was done more to impress the Soviet Union than to cow Japan, they say. And the US President who took the decision, Harry Truman, was culpable, they add.

“He knew he was beginning the process of annihilation of the species,” says Peter Kuznick, director of the Nuclear Studies Institute at American University in Washington DC, US. “It was not just a war crime; it was a crime against humanity.”
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[The conventional explanation of using the bombs to end the war and save lives] is disputed by Kuznick and Mark Selden, a historian from Cornell University in Ithaca, New York, US.
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New studies of the US, Japanese and Soviet diplomatic archives suggest that Truman’s main motive was to limit Soviet expansion in Asia, Kuznick claims. Japan surrendered because the Soviet Union began an invasion a few days after the Hiroshima bombing, not because of the atomic bombs themselves, he says.
According to an account by Walter Brown, assistant to then-US secretary of state James Byrnes, Truman agreed at a meeting three days before the bomb was dropped on Hiroshima that Japan was “looking for peace”. Truman was told by his army generals, Douglas Macarthur and Dwight Eisenhower, and his naval chief of staff, William Leahy, that there was no military need to use the bomb.
“Impressing Russia was more important than ending the war in Japan,” says Selden.

John Pilger points out:

The US secretary of war, Henry Stimson, told President Truman he was “fearful” that the US air force would have Japan so “bombed out” that the new weapon would not be able “to show its strength”. He later admitted that “no effort was made, and none was seriously considered, to achieve surrender merely in order not to have to use the bomb”. His foreign policy colleagues were eager “to browbeat the Russians with the bomb held rather ostentatiously on our hip”. General Leslie Groves, director of the Manhattan Project that made the bomb, testified: “There was never any illusion on my part that Russia was our enemy, and that the project was conducted on that basis.” The day after Hiroshima was obliterated, President Truman voiced his satisfaction with the “overwhelming success” of “the experiment”.

We’ll give the last word to University of Maryland professor of political economy – and former Legislative Director in the U.S. House of Representatives and the U.S. Senate, and Special Assistant in the Department of State – Gar Alperovitz:

Though most Americans are unaware of the fact, increasing numbers of historians now recognize the United States did not need to use the atomic bomb to end the war against Japan in 1945. Moreover, this essential judgment was expressed by the vast majority of top American military leaders in all three services in the years after the war ended: Army, Navy and Army Air Force. Nor was this the judgment of “liberals,” as is sometimes thought today. In fact, leading conservatives were far more outspoken in challenging the decision as unjustified and immoral than American liberals in the years following World War II.
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Instead [of allowing other options to end the war, such as letting the Soviets attack Japan with ground forces], the United States rushed to use two atomic bombs at almost exactly the time that an August 8 Soviet attack had originally been scheduled: Hiroshima on August 6 and Nagasaki on August 9. The timing itself has obviously raised questions among many historians. The available evidence, though not conclusive, strongly suggests that the atomic bombs may well have been used in part because American leaders “preferred”—as Pulitzer Prize–winning historian Martin Sherwin has put it—to end the war with the bombs rather than the Soviet attack. Impressing the Soviets during the early diplomatic sparring that ultimately became the Cold War also appears likely to have been a significant factor.
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The most illuminating perspective, however, comes from top World War II American military leaders. The conventional wisdom that the atomic bomb saved a million lives is so widespread that … most Americans haven’t paused to ponder something rather striking to anyone seriously concerned with the issue: Not only did most top U.S. military leaders think the bombings were unnecessary and unjustified, many were morally offended by what they regarded as the unnecessary destruction of Japanese cities and what were essentially noncombat populations. Moreover, they spoke about it quite openly and publicly.
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Shortly before his death General George C. Marshall quietly defended the decision, but for the most part he is on record as repeatedly saying that it was not a military decision, but rather a political one.