By using the eye for an eye saying, it was absolutely warranted. They bombed Pearl Harbor, which was unacceptable. America proved its military might many times over, and so the Japanese should never have interfered. Also, under the given circumstances of the pressure of World War 2, bombing Japan not only would cease the Japanese military, but would also strike fear into the other Axis powers. We won the war because of that decision.
While this was the only act of nuclear war to date, this was the most definitive act to end a war that the world has ever seen. Europe had crumbled and Japan was still holding strong to continue the War in the Pacific. The United States ordered them to surrender or there would be swift action. After the massive life lost on both sides, the bombing was the knockout punch. Many lives were affected by the two bombings, but many more would have been if they hadn't have happened.
I believe the bombing of Hiroshima and Nagasaki by the United States during World War Two was warranted. The Japanese government was refusing to surrender and they were sending countless numbers of their own men to die. The bombings were a sort of shock and awe to demonstrate how much futility there was in continuing to fight.
The tragic bombing of Hiroshima and Nagasaki by the United States was unwarranted. Sources say the Japanese already had plans in place to surrender to the allies, so there was no need to bomb. Also, the fact that the United States government had not fully tested and accounted for the affects of using such large bombs makes this act especially heinous and irresponsible.