President Harry Truman's use of the atomic bomb on Hiroshima and Nagasaki in Japan during World War II is the most controversial decision in history. While it was undoubtedly a difficult decision, it was indeed necessary to end this six-year war that had devastated the world. While many critics argue that the bomb was used primarily as an act of revenge against Japan, simplifying such a crucial moment in human history downplays the real risk that invading Japan posed to the United States. While avoiding tense relations with other Allied countries, Truman had to evaluate the possible danger posed by the Soviet Union in the postwar world. Furthermore, the possibility of an arms race, the moral implications of using this weapon, and the number of American lives that might be lost by invading Japan were among the numerous pros and cons that Truman had to consider when contemplating its use. of this powerful weapon never before unleashed on humanity. The purpose of developing this weapon was first and foremost to win the war as quickly as possible. In addition to ensuring world peace, the future of the United States as a world leader was also at stake. In 1939, President Franklin Roosevelt appointed a committee to research the possibility of using atomic energy for military purposes. When the United States entered the war in December 1941, this research was given priority and the project was extended throughout the war. Due to the extremely sensitive nature of the Manhattan Project, only a select few knew of the plan to develop the atomic bomb. The support of allied countries was also crucial to maintaining the integrity of the project. The United States collaborated with Great Britain and...... middle of paper ......d through widespread hysteria and hostility between the two superpowers. The United States' role as a peacemaker was forever challenged by the use of this weapon and for the remainder of his time as president, Truman would fight to stop the spread of communism and subsequent presidents' greatest fear was the outbreak of a nuclear war. . Truman's decision changed the course of world history. From a moral point of view, the loss of innocent lives is never right. The enormous cost of using this weapon was the lives of hundreds of thousands of innocent Japanese civilians due to the immediate and long-term effects of the bombs. Despite the moral arguments against this choice, it was the best one for the American cause. Truman's obligation was first and foremost to the American people, and as commander in chief, he made the decision he thought was best for his constituents.