"Using World War 2 as an example, the Army Air Forces immolated Japanese cities with white phosphorus and napalm before the atomic bomb was available. In Tokyo alone, hundreds of thousands of people were reduced to ash, and the glow of the firestorm was visible from hundreds of miles away. Those actions, followed by the atomic bombing, are marginally controversial today but largely accepted as 'ok'."
How else would you deal with an enemy that would not give in? Most people fail to understand that the axis was all in, in every way, shape and form. When it comes to the Japanese, they flat out were not going to give up. Their will had to be broken, somehow, someway.