Out of context it may seem that disgraceful.
In context, different.
The U.S. didn't attack Japan at Pearl Harbor.
And while the U.S. had non-nuclear options, some military experts have estimated if instead of nukes the U.S. had attempted to march to Tokyo in more conventional military combat style,
based on the casualty profile of the Pacific islands, the number of human lives lost might have been even larger.
There's room for speculation.
But history makes clear, the U.S. had a global nuclear weapons monopoly for long enough to have attempted global conquest.
It didn't.
I understand your perspective, but I see it from a different angle.
Japan has insufficient farm, mineral, or energy resource on its island limits, and what Admiral Perry's fleet visit did was threaten Japan.
Which forced Japan to then try to expand on the mainland and other Islands.
So while we think nothing of having naval bases in Hawaii, to Asians, that is an illegal invasion that threatens all of Asia.
The US then was criminal in imposing economic sanctions on Japan.
First with the 5-5-3 treaty, and later with embargoes on steel, oil, and coal.
The US supported Chang Kai Shek, who the Chinese considered an evil dictator.
They preferred the emperor that Japan supported.
After reading Truman's "Potsdam Diaries", it said that when Stalin told Truman about how Japan was trying to surrender through the Russian embassy in Japan, that Truman told him to pretend confusion, so that we could have the time to test our nukes.
Meaning we knew no invasion was necessary, since Japan was already trying to surrender a year earlier.
And the timing was not that simple.
The Russians were always almost equal to the US nuclear program, and conducted their first test detonations in 1949.
We did not detonate our first thermonuclear weapon until 1952.
So we really did not have much of an advantage, considering how Klaus Fuchs, Greenglass, the Rosenbergs, etc. kept Russia informed.