During the last stages of World War 2 the U. dropped leaflets throughout Japan asking for surrender. The consequences included a "Rain of ruin from the air, the likes of which have never been seen on this earth". The Japanese public had been used to leaflet threats, so the public chose to ignore this threat as well. But On August 6, 1945, the U.S. dropped the first atomic weapon in warfare of Hiroshima. Another bomb fell over Nagasaki three days later. Together, the bombs took an estimated 340,000 lives from initial impact and fallout. But it was necessary for the U.S. to drop those bombs to ultimately save lives and secure the future.
The main point against the usage of the bombs is the idea that Japan would have eventually surrendered. Unfortunately, this scenario would never have played out. The Japanese of this era were bound by a strict honor system. Everything a Japanese person did revolved around honor. Japan had never lost a war and had never been invaded. For this reason, the populace of Japan was prepared to fight to the death rather than surrender. In the Battle of Okinawa, over 100,000 Japanese were killed in battle, over 200,000 sealed in caves (often voluntary) and roughly 2,000 surrendered. The Japanese played this game to the death in hopes the U.S. would tire of war, and not force upon Japan an unconditional surrender.
The only other option available to end the brutal Japanese expansion and murder was a full scale invasion of Japan. This had already been planned out in the last few months of the war. Codenamed Operation Downfall, this invasion would have been the single largest operation in the history of the world, dwarfing the invasion of Normandy.
Operation Downfall had two main stages. The first stage, Operation Olympic, consisted of a massive invasion of the southern island of Kyuusu. Over 750,000 ground troops would be employed with a massive air campaign as support. Over 572,000 casualties were expected for the American side alone.