What reasons did opponents of using the bomb offer to Secretary Stinson?

Opponents of using the atomic bomb, including some military and political leaders, argued that it was unnecessary to end World War II since Japan was already on the brink of surrender. They believed that a demonstration of the bomb's power or continued conventional warfare could achieve victory without the massive civilian casualties the bomb would cause. Additionally, there were ethical concerns about the moral implications of using such a devastating weapon and its long-term consequences for global security and nuclear proliferation.