Why did supporters of using the atomic bomb reject the idea of dropping one on a deserted island?

They did not want to waste one of the remaining bombs.

Explanation:

In World War II, the U.S. determination to use an atomic weapon on Hiroshima and Nagasaki arose diverse outlooks among American society.

President Harry S. Truman asserted he was warned not to drop the bomb as only a technical demonstration, like in a deserted island. The committee constituted to analyze the use of these new weapons stated that it wouldn´t be enough to settle the war. According to them, the atomic bomb had to be used against the enemy target as soon as poss

the deaths of over a million communist soldiers

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