Did the military situation justify a surprise attack with the atom bomb?

By early in 1945 Germany had surrendered and the United States was able to focus on the war in the Pacific. Japan was suffering from a serious lack of oil and was having trouble producing more armaments with which to fight. America had a strong position in the Pacific and was moving ever closer to Japan by the time Germany surrendered. In the February of 1944 Admiral Chester Nimitz had already been successful in a series of …

…upon its completion that he would save more American lives by dropping the atom bomb than by means of a land invasion due to the incredible spirit of the Japanese army. This is part of a three-part assignment. The other two pieces are Why did the U.S. drop the second bomb so close to the first? and Did the U.S. want to surprise Japan or the Soviet Union? Thank you for your time