The devastating true scale of nuclear weapons began on July 26, 1945, when the Allies demanded the unconditional surrender of Japan, warning of "prompt and utter destruction" if compliance failed. Japan ignored this ultimatum.
By summer, the Allies' Manhattan Project had developed two atomic bombs: the uranium-based "Little Boy " and plutonium-based "Fat Man." A top-secret mission saw six B-29 bombers heading to Hiroshima, with the Enola Gay carrying Little Boy. It was released over Hiroshima on August 6, releasing 15 kilotons of TNT, devastating a 1.6 kilometers radius.
Three days later, Bockscar dropped Fat Man on Nagasaki, resulting in a 21-kiloton explosion. These bombings led to 129,000 to 226,000 deaths, prompting Japan's surrender on August 15, 1945, ending World War II and igniting a nuclear arms race, especially between the USA and the Soviet Union.
The US's most powerful nuclear weapon today is the B83, with a maximum yield of 1.2 megatons of TNT, designed for enhanced safety and varied applications including the "Nuclear Bunker Buster" project and asteroid impact avoidance strategies.
Castle Bravo, detonated on March 1, 1954, remains the most powerful device tested by the US, yielding 15 megatons. The Soviet Union responded by developing the Tsar Bomba, detonated on October 30, 1961, with a yield of 50 megatons, marking the largest human-made explosion.
The nuclear arms race led to the development of extensive arsenals capable of mutual assured destruction (MAD), a doctrine suggesting that nuclear conflict would result in the annihilation of both attacker and defender, effectively deterring outright nuclear war. These developments have left a lasting impact on global politics and security.