Geoffrey Roberts looks at how and why we ushered in the age of the megaton bomb.


Fallout from first nuclear attack lingers

Tomorrow is the 70th anniversary of the Hiroshima bombing, which killed 70,000. Geoffrey Roberts looks at how and why we ushered in the age of the megaton bomb.

Fallout from first nuclear attack lingers

Fears about the existential threat of nuclear weapons have captured fewer headlines since the end of the Cold War.

Yet the world’s nuclear powers retain the capacity to wipe out humanity many times over. Russia and the US keep thousands of nuclear weapons, while Britain, France, China, India, Israel, and Pakistan each has hundreds in their stockpiles.

Nuclear proliferation remains the most intractable problem of world politics. It took a decade of tortuous negotiations to reach agreement with Iran about its nuclear programme. Iran has now pledged to devote its efforts only to nuclear-generated energy but the recent deal is unlikely to stop it acquiring an atom bomb in the future. There is no doubt that in the coming decades the 1970 Nuclear Non-Proliferation Treaty will be tested to its possible breaking point.

The nuclear age dawned more than 70 years ago when the US successfully tested an atom bomb in the New Mexico desert. Three weeks later, on August 6, 1945, the Americans exploded an atom bomb above the Japanese city of Hiroshima, killing 70,000 people instantly and destroying 70% of the city’s buildings. Nagasaki was attacked with equally devastating effect on August 9.

The Americans had one more bomb in the pipeline but the Japanese sued for peace on August 14. The next day, Emperor Hirohito broadcast to his people that the war had not developed to Japan’s advantage and the enemy now possessed “a new and most cruel weapon”.

The atom bomb was developed by the Manhattan Project under the leadership of American physicist Robert J. Oppenheimer. Years later, Oppenheimer recalled that when he witnessed the New Mexico test, a line from the Hindu Bhagavad-Gita scripture came to mind: “Now I am become Death, the destroyer of worlds.” The race to build a nuclear bomb began during the early years of the Second World War.

Japan had a nuclear research programme, as did the Soviet Union, but the main contest was between the western allies and Nazi Germany. The German nuclear effort was led by theoretical physicist Werner Heisenberg, pioneer of quantum mechanics and devisor of the uncertainty principle. Fortunately for the allies, Heisenberg’s project depended on a heavy water plant that was sabotaged by the Norwegian resistance in 1943.

The Manhattan Project’s goal was to develop an atom bomb before the Germans and to use it against targets in Germany. Hundreds of thousands of Germans had been killed by conventional bombing. Atomic weapons were seen as a more efficient and less costly method of achieving the same result.

While Germany surrendered in May 1945, war still raged in Asia and it was likely — but not inevitable — that nuclear weapons would be used against the Japanese, whose cities had already been subjected to horrific fire-bomb raids that killed nearly 1m civilians.

By summer 1945, some scientists were having doubts about the morality and necessity of atom-bombing Japan, a country already facing imminent defeat through conventional warfare. Top-level US decision-makers considered alternatives, such as threatening Japan with the bomb or giving a test demonstration of its power.

But the momentum in favour of using every available weapon to end the war as soon as possible was too great.

The final decision to use the atom bomb was taken by President Harry Truman, who knew nothing about the Manhattan Project until he assumed office when Franklin Delano Roosevelt died in April 1945. Three months later, the new president found himself facing a momentous decision.

Truman claimed he authorised the bombing of Hiroshima and Nagasaki for military reasons — to force Japan to surrender and to save the tens of thousands of American lives that would have inevitably been lost during an invasion of the Japanese home islands.

It was during the Allies’ Potsdam conference in Berlin that Truman received news of the successful atom bomb test. He informed Stalin but the Soviet dictator feigned disinterest. In reality, the Manhattan Project was riddled with Soviet spies and Stalin probably knew more about the atomic bomb than did Truman.

After Potsdam, Stalin authorised a breakneck-speed project to develop a Soviet atom bomb and, much to world’s surprise, the Soviets were able to test their first nuclear device as early as August 1949.

At Potsdam, the Allies agreed to threaten Japan with “prompt and utter destruction” if it did not surrender immediately. The Japanese failure to comply was rapidly followed by the attacks on Hiroshima and Nagasaki. As the atomic bombs were being deployed, the Soviet Union launched a massive land attack on Japanese forces in Manchuria. It was the dual shock and awe of the Red Army onslaught and the devastation caused by the American bombs that precipitated Japan’s unconditional surrender.

In the aftermath of the Second World War, efforts were made to bring nuclear weapons under international control, but talks failed because America was determined to retain its nuclear monopoly for as long as possible. The Soviets campaigned for the prohibition of weapons of mass destruction while continuing to construct their own. The British followed the Soviet example in the 1950s, as did the French and the Chinese in the 1960s.

Astonishingly, those five countries remain the only official nuclear states in the world. Most other countries have signed up to the Non-Proliferation Treaty, under which states pledge to remain non-nuclear, an idea first proposed by Irish foreign minister Frank Aiken in 1958.

However, non-signatories include the so-called “secret” nuclear states of India, Pakistan, Israel, and North Korea, which withdrew from the treaty and conducted its first nuclear test in 2006.

Although the devastation, deaths, and radiation effects at Hiroshima and Nagasaki served as a shocking climax to the Second World War, the atomic weapons of the 1940s were not game-changers in military terms. The real nuclear revolution did not occur until the 1950s when thermonuclear weapons, or H-Bombs, were developed that were a thousand times more powerful than the atom bombs dropped on Japan.

Oppenheimer opposed such super-bombs. He favoured a de-escalation of the nuclear arms race and baulked at the creation of such vast destructive power — which could destroy the whole world. This stance cost Oppenheimer his security clearance amid accusations that he harboured communist sympathies. Oppenheimer was one of many scientists — western and Soviet who came to regret their role in the genesis of the atomic bomb.

Geoffrey Roberts is professor of history at University College Cork

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