If they would have invaded Japan the war could have gone on for several more years; which meant even more casualties and money spent towards war. They chose to use the atomic bomb for a quicker end to the war- which changed the idea of war forever.
The U.S. government rejected the idea of invading Japan in World War II due to high casualty estimates, the effectiveness of the newly developed atomic bomb, and the fierce resistance posed by Japanese forces. Instead of a costly invasion, they used atomic bombs to bring a swift end to the war. Political considerations also played a role in this decision, signaling a shift in post-war dynamics.
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