The Truman administration calculated that up to 1 million American servicemen would be killed in an invasion of the Japanese home islands, not to mention the civilian carnage that would result - you just have to look at the death tolls on both sides at Iwo Jima and Saipan to understand why. Add to that intelligence that the Nazis had transferred their nuclear weapon research materials to the Japanese in early 1945 and you can easily understand the motivation to use the atomic weapons. The fact that it took two such attacks before Emperor Hirohito could convince his own government to surrender should tell you all you need to know about the mentality of the Japanese at that time. Tragic of course, but the alternatives were worse.
Shaffir to Herzog: Opposition failed to show leadership in political battles against PM (Haaretz)
from the article: A mosque in the Temple