Lamont Lansing’s book, Day of Trinity, quotes J. Robert Oppenheimer, then near the end of his life:
“As for how we used it, I understand why it happened and appreciate with what nobility those men with whom I’d worked made their decision. But I do not have the feeling that it was done right. The ultimatum to Japan was full of pious platitudes…Our government should have acted with more foresight and clarity in telling the world and Japan what the bomb meant."
via Wired