Hiroshima and the Cold War


After Hiroshima and Nagasaki nothing was ever the same again ... the use of the atomic bomb in August 1945 changed the world more dramatically than any single event before.

Chronicle of the World (1989).


When I first started teaching, we just taught that the atomic bomb brought the war to an end.  Only recently have we come to appreciate that the last shot of the Second World War was also the opening scene of the Cold War – that the Bomb was a cause as much as a conclusion.

British historian John D Clare, writing in 2010.




The Atomic Bomb - a timeline.


PBS - straightforward explanation of the diplomatic results of the Bomb.


The Day the Cold War broke out - how the atomic bomb changed Truman's relations with the Soviet Union.


Historian Walter LaFeber on the effect of the Bomb on the Potsdam Conference


Stalin's reaction to the bomb - an interview with the American ambassador two days after Hiroshima.

Interview with David Holloway - one historian's interpretation of Stalin's reaction.


Truman's Diary and Papers - an insight into his thinking about the Bomb. 


Did Truman tell Stalin? - a collection of documents which investigate whether Truman 'duped' Stalin about the Bomb at Potsdam.


1.  WHAT: Dropping the bomb

By May 1945, the Japanese were clearly losing the war in the Pacific; they started making requests for a peace.  Stalin told Truman at Potsdam of 'telegram from Jap Emperor asking for peace’ (it was refused; instead the Potsdam Conference called on Japan to surrender unconditionally).  In fact, the Japanese offered to surrender on 3 August, but their offer was rejected because it wasn’t an ‘unconditional’ surrender.


Instead, on 6 August 1945, the B29 bomber Enola Gay dropped the first atomic bomb (nicknamed ‘Little Boy’) on Hiroshima.  The temperature in the centre of the bomb was 50 times hotter than the surface of the sun.  Winds swept out from the centre at 500 mph; everything in a two-mile radius was flattened.  The mushroom cloud rose to 50,000 feet.  The Americans estimated at 117,000 people were killed – the Japanese put the figure at a quarter of a million.


Three days later, on 9 August, the Americans dropped another bomb, on Nagasaki, and the Japanese surrendered.




The Hiroshima mushroom cloud, 6 August 1945,
photographed from the Enola Gay.

2.  WHY was the Bomb dropped?

For many years, (‘traditional’) historians were prepared to take Churchill and Truman’s words at face value, and accepted without question the official explanation that the bomb was dropped to end the war in Japan quickly, saving millions of American casualties (see Sources A and B). 


In 1965, however, revisionist historian Gar Alperovitz wrote Atomic Diplomacy: Hiroshima and Potsdam.  Alperovitz turned the whole question on its head, claiming: 

  1. the Japanese were on the verge of surrender in August 1945;

  2. Truman dropped the atomic bombs because he wanted to end the war before the USSR could enter the war in the Pacific and claim the lands promised them at Yalta.

  3. the bomb was dropped to impress the Soviets, and persuade them to relax their grip on eastern Europe.

For Alperovitz, Truman caused the Cold War when he dropped the Bomb. 





3.  HOW did the Bomb help to cause the Cold War?

Historians have offered two suggestions: 



Source A

To bring the war to an end, to give peace to the world … at the cost of a few explosions, seemed, after all our toils and perils, a miracle.

The end of the Japanese war no longer depended upon the pouring in of [the Russian] armies.

Winston Churchill, describing a conversation with Truman in 1945. 



Source B

Having found the bomb we have used it. We have used it in order to shorten the agony of war, in order to save the lives of thousands and thousands of young Americans.

Speech by President Truman, 9 August 1945. 

Possibility ONE:

The atomic bomb changed STALIN'S attitude.

Historians have suggested a number of ways in which the atomic bomb might have alienated Stalin:

  1. The traditional argument was that Stalin was angry because Truman did not tell him about the Atomic Bomb.  Truman, the story goes, was deliberately vague when he mentioned the Bomb to Stalin on 24 July – he just quickly mentioned in passing that the USA had ‘a new weapon of unusual destructive force.’  Truman didn't specifically call it an atomic bomb, and he certainly didn’t say he was going to use it against Japan.  Stalin merely nodded, and witnesses were convinced he hadn’t realised the implication of what he had just been told.  When the Americans dropped the bomb, the argument goes, Stalin was furious that he had been duped, and this was how the Bomb caused the Cold War (see Source C).

  2. It is almost certain, however, that this thesis is not true in such a simplistic way - all the evidence shows that Stalin knew the Americans were working on the atomic bomb.

    Soviet sources DO suggest, however, that straight after Truman told him about the ‘new weapon’, Stalin gave orders for Soviet scientists to develop their own nuclear weapon – so news of the atomic bomb DID provoke a nuclear arms race (see Source D). 

  3. There is no doubt that Stalin saw the dropping of the Bomb as directed more at Russia than Japan:  ‘They are killing the Japanese and intimidating us’ he told Molotov.  (To be fair, western politicians were hopeful it would have this effect.) 

    Stalin’s reaction, argues historian David Holloway, was to play 'hard ball', and he instructed his diplomats to take a tougher position against the west.  Then in February 1946, he gave the famous ‘Bolshoi speech’ accusing America of using its atomic advantage for imperialism.  In this way, it is claimed, the atomic bomb directly caused the entrenched positions of the Cold War. 

Source C

After the bomb was dropped, Stalin was furious. The place Russia had earned as a world power by its victory in the war had been snatched away. "Hiroshima has shaken the whole world," he is said to have told Kurchatov. "The balance has been destroyed."

Priscilla McMillan, Science and Secrecy (2004).

From a review in the New York Times of David Holloway's book: Stalin and the Bomb.



Source D

Truman informed Stalin that the United States now possessed a bomb of exceptional power, without, however, naming it the atomic bomb… Stalin did not betray his feelings and pretended that he saw nothing special in what Truman had imparted to him.  Both Churchill and many other Anglo-American authors subsequently assumed that Stalin had really failed to fathom the significance of what he had heard. 

In actual fact, on returning to his quarters after this meeting Stalin, in my presence, told Molotov about his conversation with Truman.  The latter reacted almost immediately.  ‘Let them. We'll have to speed things up.’  I realized that they were talking about research on the atomic bomb.

It was clear already then that the US Government intended to use the atomic weapon for the purpose of achieving its Imperialist goals from a position of strength in ‘the cold war’.

Georgii Konstantinovich Zhukov, The Memoirs of Marshal Zhukov (1971).

Zhukov was remembering the day (24 July 1945) when Truman told Stalin that he had ‘a new weapon of unusual destructive force’. Zhukov suggests that, not only did Stalin realise that this was the atomic bomb, but that he also realised it was directed at the Soviet Union. If Zhukov is right, the Cold War started on 24 July 1945. 




Source E

On 27 October 1945, Truman made a speech about US foreign policy, which outlined twelve key points. These included a promise that the US did not want any territory, and did not intend to go to war with any country, small or large.

However, he also announced that the USA would be seeking defensive military bases, and that he did not intend to share the secrets of the atomic bomb with anybody. The speech alarmed the British, who saw it as increasing the tension between America and the Soviet Union, and also as an affront to the close diplomatic relationship between Britain and the United States. 

This cartoon by the British cartoonist David Low appeared in the Evening Standard on 30 October 1945. 

Click here for the interpretation



Possibility TWO:

The atomic bomb changed TRUMAN'S attitude.

There are historians who think that the atomic bomb caused the Cold War, not because it provoked Stalin to seek confrontation, but because it encouraged Truman seek confrontation.

When Truman knew that he had the bomb:

  1. His attitude at the Conference became more aggressive,

  2. He switched from pro-Soviet advisors (such as Davies) to anti-communist advisors such as Stimson and Byrnes.

  3. He dropped the Bomb on Hiroshima to get the Japanese to surrender quickly, before Stalin had a chance to enter the war in the Pacific.

  4. He developed an attitude of confrontation - 'I'm sick of babying the Soviets'.



Did you know?

At Yalta, the USA was desperate for the Russians to join the war in the Pacific, and promised Stalin spheres of influence in Manchuria and North Korea to do so.

News of the successful test allowed Truman to renege on this agreement.  On 7 August, the day after Hiroshima, Stalin brought forward his plans and ordered the Soviet forces to attack Japan immediately – he knew he had been upstaged.


1.   Do Sources A and B prove that Truman dropped the bomb to save American soldiers' lives?

2.   Do you trust Source D?

3.   Did Hiroshima cause the Cold War ... and if so, how?  Discuss which of the two possibilities you think most closely fits the facts.