I respectfully disagree that it's indefensible. It was either 100,000 Japanese
civilians in those 2 cities OR million or more American casualties.
AND if the invasion had taken place, millions and millions of Japanese
civilians would've died also.
I respectfully disagree with your defense as it's speculative.
Iwo Jima?
And ALL other Japanese islands that had to be conquered?
## EDIT
I don't mean to be dismissive but anyone with even remote knowledge of what went on to recapture all the Japanese held islands in the Pacific during the WW2 will say the nukes were needed.
On all the islands that US Marines/soldiers fought on to recapture from Japan, Japanese units were usually wiped to the last man. And this kind of resistance to the last man was repeated on every single island.
Example, Saipan island.
Out of 31,000 Japanese soldiers, only 921 were captured. 24000 were killed and 5000 committed suicide. 22000 Japanese civilians died, mostly from suicides.
