In addition, a little off topic, speaking of Hiroshima, President Truman felt guilty in the years
after 1945 over the fact that 10,000's of civilians perished in Hiroshima because of his decision.

In fact I suspect that his guilt
may have played a role in his reluctance to see tactical nukes
and their delivery systems developed
in the years between 1945-1950.
It was only with Stalin detonating his own atomic device in 1949, and the Korean War a year later, which convinced a reluctant Truman to develop the even more horrible (strategic) H-Bomb and developing tactical nukes as well.
It was in 1950 that Truman authorized Von Braun's team
to develop the Redstone tactical nuke rocket, even though Von Braun had been pushing for the development of a Redstone type rocket since 1946.
Imagine what would have resulted if Truman had approved
of the development of a 200 mile range tactical nuke missile in 1946 instead of 1950.
The US could have launched a miniature artificial satellite as early as 1950-1951.