August 6, 1945: the day the world changed forever Something changed forever on August 6, 1945 when, for the first time, the world witnessed the explosion of an atomic bomb. As that fateful day dawned, a B-29 American bomber named the Enola Gay took off from an island in the Pacific Ocean heading for Japan, which had prompted the US" entry into World War II by attacking Pearl Harbour some three and a half years earlier. At 8:15 AM local time its crew dropped an atomic bomb, nicknamed "Little Boy" on the Japanese city of Hiroshima. Those aboard the watched as the city, inhabited by 350,000 people, disappeared into dust. Robert Lewis, the co-pilot of the American bomber commented in the flight log: "My God, what have we done?" The bomb caused the immediate death of 70,000 people. This figure increased to an estimated 200,000 as more victims succumbed to nuclear radiation. The explosion destroyed every building in a radius of 2,5 km; it broke windows 16 km away, while the force of the blast could be felt as far away as 60 kilometres. The mushroom cloud created by the nuclear explosion hung in the sky over Hiroshima for hours. No Comment Video- Japan marks 68th anniversary of Hiroshima At first, the Japanese leadership couldn't identify the "sinister cloud" over Hiroshima. But they soon knew that the destruction was likely caused by an atomic bomb, a realisation that shocked Japan's leaders, who were unaware that their American enemies were at such an advanced stage of nuclear research and development. The bombing and its nature were confirmed by President Truman himself 16 hours after the attack; he declared that an American airplane had dropped a bomb on Hiroshima and threatened to launch more similar attacks if Japan didn't accept terms for peace and end the war. Three days after Hiroshima was destroyed, on 9 August, another American plane dropped an atomic bomb named "Fat Man" on Nagasaki, causing the immediate death of another 40,000 people. Japan laid down arms on 15 August, thus ending World War II. Click here to see the destructive range of various nuclear warheads. You can see the result of the attack on Hiroshima by clicking here. The pilot of the Enola Gay, the then-30-year-old Paul Tibbets, never repented the role he played in the Hiroshima bombing. As he explained in an interview, he felt it was his patriotic duty to accomplish the mission assigned to him. Do you have any idea how many American lives would have been lost had we launched a ground invasion of Japan, instead of dropping the bomb? And how many Japanese lives? I sleep so well because I know how many people got to live full lives because of what we did. He added: "If I had been asked to do it, I would have done it in a second (...) If the Germans had not surrendered, I would have flown the bomb over there." Tibbets was afraid that his funeral would be disturbed by demonstrators so he instructed that when he died, there would be no ceremony and that no headstone should mark his grave. President Truman was criticised for his decision to drop the bomb; just three days before the Hiroshima bombing, he admitted that Japan was "seeking the way of peace." While some of Truman's political advisors didn't think the bombing was necessary, they failed to convince their commander-in-chief. Some experts have since speculated that Truman wanted to show the power of America to the USSR, and he wanted the atomic bomb to be the launch of the Cold War. Project Manhattan Encouraged by physicist Léo Szilárd, President Roosevelt decided to launch Project Manhattan in 1942. It was a joint venture by the United States, Great Britain and Canada, and aimed to develop a nuclear weapon. The leader of the project was Robert Oppenheimer. Enrico Fermi and Leo Szilárd were charged with the reactor planning, Jenő Wigner with the chemical problems, Janos Neumann with mathematical calculations. Beside the Hungarian physicists, several American, Italian and other researchers participated in the project. The military leader of the Manhattan project was Lieutenant General Leslie R. Groves, a military engineer. The entire cost of the project was about 300,000 dollars, a modest amount compared to other military research. The father of the theory of nuclear chain reaction, Hungarian phycisist Leó Szilárd, wrote a petition to President Truman in July, 1945 pleading with him not to drop a bomb on Hiroshima. The petition was signed by 68 other scientists. He had also written a letter to President Franklin D. Roosevelt after the capitulation of Germany in which he recommended the restriction of atomic bomb use. But Roosevelt died before he could read the letter. While Szilárd argued against the use of nuclear weapons, he was the very man who campaigned for their construction. He wrote a letter to Roosevelt in August 1939, urging the American President to overtake Germany in the race to build nuclear weapons. In the document he explains that it is possible to create a nuclear chain reaction, thus an atomic bomb, and detailed the destructive potential of such weapons. To show his approval, Albert Einstein signed the letter. Einstein, who hated the Nazis, championed the case for nuclear weapons after Leo Szilárd and Jenő Wigner (another Hungarian physicist) had paid him a visit and explained him their discovery. The number of inhabitants of Hiroshima reached the pre-war level in 1960. In our report you can visit the once- classified Hiroshima photos in the frame of an exhibition. You can watch all the nuclear tests ever carried out on Earth in this video. The nuclear tests are shown as small colourful flashes with the matching year and the name of the country that initiated the test. Treaties and negotiations on mutual nuclear disarmament between Russia (and its predecessor, the Soviet Union) and the United States Treaty between the United States of America and the Russian Federation on Measures for the Further Reduction and Limitation of Strategic Offensive Arms also known as the New START Treaty. Under the terms of the Treaty, the US and Russia must meet central limits on strategic arms by February 5, 2018. Each Party has the flexibility to determine for itself the structure of its strategic forces within the aggregate limits of the Treaty. Aggregate limits: 1,550 warheads. Warheads on deployed Intercontinental Ballistic Missile (ICBMs) and deployed Submarine-Launched Ballistic Missile (SLBMs) count toward this limit and each deployed heavy bomber equipped for nuclear armaments counts as one warhead toward this limit. A combined limit of 800 deployed and non-deployed ICBM launchers, SLBM launchers, and heavy bombers equipped for nuclear armaments. A separate limit of 700 deployed ICBMs, deployed SLBMs, and deployed heavy bombers equipped for nuclear armaments. Date of first tests United States: 16 July 1945 Remains the only country to have used nuclear weapons against another nation. Russia: 29 August 1949 The Soviet Union was the second nation to have developed and tested a nuclear weapon. United Kingdom: 3 October 1952 The United Kingdom has conducted 45 tests, 21 in Australian territory France: 13 February 1960 France`s first nuclear test was motivated by the Suez Crisis diplomatic tension. It was also relevant to retain great power status during the post-colonial Cold War. China: 16 October 1964 China conducted 45 tests, (23 atmospheric and 22 underground.) India: 18 May 1974 The official number of Indian nuclear tests is 6. Pakistan: 28 May 1998 Pakistani Prime Minister Zulfiqar Ali Bhutto promised in 1965 that if India can build nuclear weapons then Pakistan would too, "even if we have to eat grass." North Korea: 9 October 2006 North Korea was a party to the Nuclear Non-Proliferation Treaty, but announced a withdrawal in 2003, after the United States accused it of having a secret uranium enrichment program. Formerly possessed nuclear weapons South Africa: Produced six nuclear weapons in the 1980s, but disassembled them in the early 1990s - Belarus, Kazakhstan, Ukraine: After the collapse of the USSR, all transferred their warheads to Russia Countries suspected of having nuclear weapons Israel: Widely believed to be the sixth country in the world to have developed nuclear weapons - Iran: Believed to be pursuing a nuclear weapons program More about: Nuclear research, Nuclear weapons, World War II