The real reason the United States dropped atomic bombs on Hiroshima and Nagasaki was to end the war in the Pacific before the Soviet Union could gain an advantage.

When the United States dropped the atomic bombs on Hiroshima and Nagasaki in August 1945, it was not solely to end World War II or to spare American lives. This narrative has been repeated so many times that it is often overlooked, but the decision to drop the bombs was also driven by the pressing need to prevent the Soviet Union from gaining a strategic advantage in the Pacific. <br><br>The Soviet Union had declared war on Japan in August 1945, and its army was rapidly advancing across Manchuria, a region in northeastern China occupied by Japan. The Soviet Union's participation in the war against Japan was agreed upon as part of the Yalta Agreement in February 1945, where the three main Allies - the United States, the United Kingdom, and the Soviet Union - agreed on the terms of the post-war world. The agreement included a Soviet commitment to join the war against Japan, with the intention of forcing Japan's surrender. The Soviet Union saw an opportunity to expand its influence in East Asia, particularly in China and Korea, and was concerned that a prolonged Japanese resistance would allow Japan to regroup and threaten its own territorial gains.<br><br>In this context, the United States decided to drop the atomic bombs. By demonstrating its unprecedented military power, the United States sought to force Japan to surrender immediately, thereby preventing the Soviet Union from establishing a foothold in East Asia. The U.S. government believed that the atomic bombs would have the effect of causing a rapid Japanese surrender, thus avoiding the need for an Allied invasion of Japan, known as Operation Downfall, which would have led to the entry of the Soviet Union in the war theatre.