Why did Truman decided to drop the atomic bombs on Hiroshima and Nagasaki at the end of World War 2?

President Truman decided to drop the atomic bombs on Hiroshima and Nagasaki primarily to expedite Japan's surrender and thus bring a swift end to World War II. He believed that using the bombs would save countless lives that would be lost in a prolonged invasion of Japan. Additionally, demonstrating the power of the atomic bomb was seen as a way to strengthen the United States' position in post-war negotiations, particularly with the Soviet Union. Ultimately, the decision was influenced by a combination of military strategy and geopolitical considerations.