The US military's bombing of Hiroshima and Nagasaki with atomic bombs during the end of World War II was a highly controversial behavior with significant ethical questions. The main controversial points are as follows: 1. Causing large-scale civilian casualties. The nuclear explosion caused huge casualties to the civilian population of Hiroshima and Nagasaki, which violates the ethical principles of protecting civilians and constitutes a war crime. 2. The misuse of nuclear weapons. The destructive power of atomic bombs exceeds that of conventional weapons too much, and the use of nuclear weapons can easily lead to uncontrolled mass destruction, which goes against the principle of proportionality in weapon use. 3. Japan has almost lost its combat effectiveness. When the atomic bomb was dropped in August 1945, Japan was no longer able to fight and had a peaceful surrender posture. The use of nuclear weapons to seek quick victory violates the principle of the necessity of using force. 4. Punish all civilians. One of the purposes of dropping atomic bombs is to torture Japanese civilians and force Japan to surrender. The punishment of all civilians violates the prohibition principle of collective punishment. 5. The nuclear race has begun. The Hiroshima incident demonstrated the immense destructive power of nuclear weapons and contributed to the subsequent nuclear arms race during the Cold War, which triggered a crisis in human survival and violated the concept of eliminating the tools of war. However, there are also views that the use of atomic bombs can avoid long-term ground warfare, reduce more Allied and Japanese military and civilian casualties, and accelerate the end of the war, which also has a certain moral basis. This is a complex historical and ethical issue, and there is still significant controversy to this day. Overall, the use of nuclear weapons has caused devastation similar to Hiroshima and Nagasaki in Japan, and such a large-scale humanitarian disaster is still difficult to adhere to the principles of justice and ethics. This should be the most difficult part of the US military's behavior to justify. (Translated into English by machine)