A Gallup poll has 57 percent of people in the US approving use of the atomic bomb on Hiroshima and Nagasaki, and 38 percent disapproving. In August 1945, the month that the bombs were dropped it was 85 percent approving and 10 percent disapproving.
Tsuyoshi Hasegawa has written a book, published in 2005 by Harvard University Press, titled Racing the Enemy that describes events and attitudes the led to use of the bombs.
The story here begins on 28 November 1943. Roosevelt, Churchill, and Stalin met at Teheran – in Soviet-occupied Iran – and Stalin pledged to enter the war against Japan following the defeat of Germany. The Soviet Union and Japan had a Neutrality Pact. Japan took the pact seriously. They had enough trouble without warring also against the Soviet Union.
Tsuyoshi Hasegawa writes that into 1944 "the Japanese Imperial Army was adamantly clinging to the course of the war." A small minority formed a "peace party," led by a rear admiral, Takagi, who believed the US would be satisfied with the creation of a peaceful and cooperative Japan.
Another conference with Roosevelt, Churchill and Stalin took place at Yalta – in Crimea – in February 1945. There they decided that Japan should surrender unconditionally. What that described in specifics was left for future consideration.
The Battle of Okinawa began in late March 1945. The Japanese considered Okinawa to be Japanese homeland. Indeed, its population was Japanese. Hasegawa writes that by April 1, when US troops were landing on the island's Kadena Beach, it was already "clear that Japan was losing the war," but Emperor Hirohito, "rather than face this obvious fact," was for "waging a decisive battle on Okinawa." He hoped that by inflicting tremendous damage on the Allies, Japan could gain favorable terms to end the war."
On 3 April, the Pentagon directed General MacArthur, the US commander in the Pacific region, to lay plans for the US move northward beyond Okinawa to one of Japan's larger and more major home islands – Kyushu.
On 12 April, Roosevelt died. Vice President Truman became President. US historian Melvyn Leffler, a professor at Virginia University, describes the new president's style:
Because he was insecure and fearful of displaying his own ignorance, he hesitated to discuss his views and rarely thought through a problem aloud. Almost everyone commented on his snap judgments. He conveyed a sense of authority, but at the expense of thoughtfulness and consistent policy. (Quoted by Hasegawa, p 61.)
On 25 April, President Truman was presented "the first full report" on the bomb project under way in New Mexico – a matter of secrecy (but not to Stalin, thanks to spying). On May 1, President Truman approved a recommendation by Secretary of State Henry Stimson to establish an Interim Committee regarding the Bomb. Use of the bomb, like many decisions by a president, was to be a
Germany surrendered "unconditionally" on May 7. The Allies were now able to concentrate on Japan. At a press conference on 8 May, after announcing Germany's surrender, Truman warned the Japanese that continued resistance would bring it "utter destruction to its war production, and he declared that the US would fight "until the Japanese military and naval forces lay down their arms in unconditional surrender."
Japan's Supreme War Leadership Council chose to posture strength and determination. It spoke of its determination "to continue the war until the objective of the Greater East Asia War is achieved." On radio, Baron Suzuki, Japan's last wartime prime minister, according to Hasegawa, called on the Japanese "to continue the war with the spirit of a kamikaze pilot."
As for the emperor, Hasegawa writes that with Okinawa headed for defeat Hirohito chose "to jettison all conditions of surrender but preservation of the kokutai, which translates into the survival of national and cultural identity. And for its preservation Hirohito was, writes Hasegawa, still willing 'to risk one last battle."
On May 12-13, at a meeting of President Truman's Interim Committee, without Truman, decided that targets for the new atom bomb would be Kyoto, Hiroshima, Yokohama, and Kokura. Stimson didn't like the idea of including Kyoto, an ancient capital of great cultural value that had not yet been touched by US air power. Hasegawa writes that Stimson "worried that the destruction of the city might provoke anti-American sentiments and solidify Japan's resolve to continue the war." Major General Leslie Groves (in charge of the Manhattan project and one of the committee members) wanted Kyoto targeted. So too did another committee member, commander of the air force, General Henry, "Hap," Arnold. Unhappy with their choices, Stimson went to Truman. Truman agreed with him, and Kyoto was removed from the list.
On 18 June, the Supreme War Council concluded that Moscow should be asked for mediation to terminate the war. On 22 June at the Imperial Palace, Prime Minister Suzuki gave his opinion that the war had to be continued "at all cost," but that he deemed it "necessary to try diplomacy as well." Hirohito was told of the Supreme War Council's position and, writes Hasegawa: "Hirohito concluded the meeting by urging ... negotiations with the Soviet Union."
The meeting at Potsdam (near Berlin) between Truman, Stalin and the British began on 17 July. In Berlin, Secretary of State Stimson had just been informed of the successful test of the Bomb in New Mexico. He informed Truman, including the news that the Bomb would be ready for a drop on Japan in early August. Stalin went to the conference concerned that the war with Japan might be over before he could get his troops moving into the Japanese occupied territory of Manchuria toward Korea. Writes Hasegawa, Secretary of State Stimson "considered the possibility of Soviet entry into the war a positive development."
In his diary, Truman wrote, "we well issue a warning statement asking the Japs to surrender and save lives. I'm sure they well not do that, but we will have given them the chance." On 26 July an ultimatum to Japan was declared, called the Potsdam Declaration, signed by Winston Churchill and President Truman. Stalin had not signed. Hasegawa writes:
The Japanese immediately noticed that Stalin did not sign the proclamation. This prompted them to continue their efforts to terminate the war through Soviet mediation rather than accepting the conditions stipulated by the Potsdam Proclamation.