A lot of people would say that this question would have an obvious
answer, but I will take the time to simplify it from the information I
have gathered below.
I will list basic points, and will just list the links to sources and
articles that will have the details you may use.
I think what makes the bombings of Hiroshima and Nagasaki
controversial is first, civilians were the targets of these raids. The
nations during World War 2 had an agreement that civilians were not to
be attacked in any way, but hits from stray weapons rounds would reach
civilians, and caused the one nation to think that the other was
already violating this agreement, so it became the trend to abandon
this policy altogether. Many are now saying the United States is still
liable today for what it did to Hiroshima and Japan and the bombing
acts are signs that the US is a cruel Imperialist monster bent on
making the world submit to it, while masquerading as a peacekeeper.
Another point some raise is that the Japanese were already going to
surrender, so the Atomic bombs were not necessary. Japans industries
were in recession and its war machine was nearly eradicated. Bombing
civilians with such powerful weapons is not considered terribly
brutal. It was like rubbing salt into an already festering wound.
Articles which can be accessed in the links I give below say that the
Japanese administration realized that they could not win the war, and
were finding ways to end it while averting an invasion by the US.
Apparently, the US got to them before they could find a way. Even US
people knew that the Japanese were more or less defeated, but they
rubbed it in with the bombs.
The Truman administration insisted that dropping the bombs was
necessary to discourage the Japanese from fighting because, as
probably demonstrated in their kamikaze attacks during the war, the
will of the Japanese was hard to break. On another note, this was also
a way to prevent more deaths of US and Allied troops. Truman was also
quoted to have said that the Japanese were repaid manifold for the
Pearl Harbor attack, giving a clue that revenge rather than sound
reasoning influenced the decision to use the bombs.
The death toll of the two bombings reached 350,000 in 1950, which
includes post-bombing radiation deaths. Some say also that the
scientists who created the atomic bomb knew of the effects of
radiation and had contributed to a brutal crime and the suffering of
people. They were considered comparable to Joseph Mengele and other
Nazi scientists who tortured Jews as part of their experiments.
These are the basic main points to the controversy of using the
Hiroshima and Nagasaki bombs. The links below will lead you to more
sources and details:
Bombing Hiroshima - a guide for students with links
The Decision to Drop the Atomic Bomb
ATOMIC BOMB: DECISION (Hiroshima-Nagasaki)
Hiroshima: Was It Necessary? The Atomic Bombing of Japan
The Atomic Bomb -- Truman's Decision
The Atomic Bomb Controversy - with links
Hiroshima Controversy (Morgana's Observatory) - William Blum article
Why bomb Hiroshima?
The Bombing of Hiroshima and Nagasaki
Atomic Bomb Controversy at Direct Essays.com
Really short summary of WWII & Hiroshima. Controversial -
Search string used on Google:
hiroshima bomb controversial
hiroshima bomb decision
I hope this has been a most helpful answer. If you have any problem
with it, do please post a Request for Clarification and I shall
respond. Thank you.