Was the bombing of Hiroshima and Nagasaki justified?

http://www.debate.org/opinions/was-the-bombing-of-hiroshima-and-nagasaki-justified

"Even though the cost was terrible, the atomic bombs used against both Hiroshima and Nagasaki were justified. The U.S. Army was preparing to invade the mainland of Japan, and this would have certainly created a situation with far more casualties than the use of the nuclear weapons. Consider also that the Soviet Union had just launched a massive attack against Japan at roughly the same time as the use of the atomic weapons. The Soviet Union could have taken Japan, which would have been extraordinarily bloody."

"First of all, they were on the losing side anyways, they would have surrendered before it. Second, we didn't have to drop it on Japan itself, we could've dropped it near the harbor and scared them into surrendering once they saw the true power of the bomb. Third, if we had just modified the Potsdam Proclamation(A proclamation that demanded that the Japanese surrendered unconditionally without any say) so that they could've agreed to something. Fourth, many Japanese were killed, yes, if we hadn't dropped it than both sides would have had casualties, but the area they bombed had six civilians for every soldier. More civilians were killed than soldiers in both of those bombings. Fifth, people around the area today still have radiation poisoning and cancer and many other illnesses because of the bomb. I really don't see why we had to drop it there if anywhere. The bomb should not have been dropped."