This statement is true and often made by those both in favor of and opposed to the use of the a-bombs to end the war. What is rarely mentioned is that the US flew many "bombing" missions in the weeks leading up to the Hiroshima and Nagasaki bombings in an effort to minimize civilian deaths. Leaflets were dropped by the hundreds of thousands which essentially translated as "If You live in one of these six cities you should flee to safety immediately because an event of unimaginable destruction is about to happen." The cities listed were those on target candidate list, but obviously the specific first targets could not be given. We tried to warn them. That is rarely noted.