Here's what one US citizen wrote in his letter to Time magazine on August 6, 1945:
The United States of America has today become the new master of brutal infamy, atrocity. Bataan, Buchenwald, Dachau, Coventry Lidice were tea parties compared the horror which we, the people of the United States of America, have dumped on the world in th form of atomic energy bombs. No peacetime applications of the Frankenstein monster can ever erase the crime we have committed. We have paved the way for the obliteration of our globe. It is no democracy where such an outrage can be committed without our consent!
Walter G. Taylor of New York City