@JimmyT: General William T. Sherman said it best: "War is cruelty, and you cannot refine it; and those who brought war into our country deserve all the curses and maledictions a people can pour out. I know I had no hand in making this war, and I know I will make more sacrifices to-day than any of you to secure peace... They are inevitable, and the only way the people of Atlanta can hope once more to live in peace and quiet at home, is to stop the war, which can only be done by admitting that it began in error and is perpetuated in pride."
Japan started the war, the U.S. ended it. Japan woke up the sleeping giant with the unprovoked bombing of Pearl Harbor that killed 2,402 non-combatant military personnel and civilians. Japan alone could have prevented the deaths of its own citizens in Hiroshima and Nagasaki by signing the paper that said: "Surrender now or face a rain of ruin from the air the like which has never before seen on this earth". Japanese leaders clearly rejected the treaty and as a result, as promised by that treaty, they received a rain of ruin from the air with the newly-developed atomic bombs and more attacks from conventional firebombs.
Also, it was not millions of enemy civilian deaths in Hiroshima. It was estimated 80,000 people died, but while most of the dead were enemy civilians (half of them were shown to be employed in munitions factories), 20,000 were enemy military combatants. Hiroshima was a legitimate military target that housed the 2nd General Army and 5th Division with 40,000 enemy military combatants stationed in the city. If it weren't for the atomic bomb, Hiroshima would have been bombed with conventional weapons, which had been going on for months long before the atomic attacks.
The U.S. Air Force was attacking Japanese cities with conventional firebombs, killing 500,000 Japanese civilians (half of them were munitions workers). The purpose of the atomic bomb was to show the Japanese we had a single bomb that could destroy as much of the enemy's war industry far more effectively than requiring 500 bombers carrying 1,000 tons of little conventional firebombs to do the job.
The Japanese was scared as hell and decided to wave the white flag and surrender. We actually broke the Japanese ability to fight, thanks to the nuclear weapons and thus, nuclear weapons did their job very well in ending the war, saving millions of U.S. lives. The Japanese war industry was partially cottage industries, or in other words, spread out throughout Japanese cities. About 50 percent of important war materials were made in residential neighborhoods in most Japanese cities.
For example, the firebombing of Tokyo reduced industrial output by about half. Those war industries could not be destroyed with precision weapons because those weapons did not exist then. High level bombing with explosive bombs had proved ineffective many times. Carpet bombing by whatever weapons we had was the only option, if the U.S. was interested in stopping the production of those war materials completely. It also has the side effect of killing many enemy workers who worked in those industries, therefore rendering the weapons manufacturing lines worthless and encouraging the enemy civilian population to withdraw from working in war industries.
Also, the Japanese government had basically made the entire country into one vast military, silly as that was, by forming the "Patriotic Citizens Fighting Corps" in March 1945, which included all men aged 15 to 60 and women 17 to 40 for military service. School girls were given bamboo sticks and farm implements and told to fight the Americans. So in theory, even by today's standards, they were combatants. Invading American troops would have been fighting Japanese soldiers and the "Patriotic Citizens Fighting Corps" house to house, city to city, street by street, etc. Can you imagine what the death toll on both sides would have been, including due to starvation, if the U.S. had invaded? Millions.
Most crewmembers of the Enola Gay feel regret that it had to happen but some them, such as Paul Tibbets and Theodore Van Kirk, said under the same circumstances, they would do it again.
There is also a moral and psychological difference between killing 100,000 persons with bombs from the sky than herding people against a wall and executing 100,000 persons. An infantryman has an ability to shoot or not shoot at close range, so he could easily see the target with his scope. If a guy goes out and stabs to death hundreds of enemy civilians without a cause, that means the enemy civilians themselves were the target. It's obviously why U.S. ground forces did not engage in mass genocide and murder of enemy non-combatants unlike the Nazis and the Japanese. Anyone who was caught doing so was court-martialed and punished.
However, when you fly an aircraft above 10,000 feet, it's very hard to tell if people on the ground are non-combatants or not. The plane goes faster and faster and you don't have time to hit the target easily.
The pilots released the bombs from their aircraft in hopes they would hit industrial factories and inevitably, whether they knew it or not, hundreds of non-combatants were killed. Does that mean non-combatants themselves were the target? No. That's the reason why aerial bombardment of enemy cities in WWII was and is a legitimate form of warfare, period. It just happened to be an extension of artillery bombardment. Yes, artillery bombardment was not as lethal as air bombardment, but it still killed thousands of enemy civilians, as shown in the Battle of Berlin when the Russians used massive artillery strikes from the great distance to drive the German defenders out of the Berlin.
That's the precise reason why it is easier to justify attacking things from the air, as opposed to killing people on the ground. People who bombed from aerial attacks on legitimate military targets and unfortunately caused collateral damage to non-combatants don't feel as much guilt as those who herded people against a wall and shot them.
Yes, in war, you always try to minimize civilian deaths, but aerial bombing in WWII can be indiscriminate due to the fact bombing technology at the time was limited by environmental conditions, plane problems, anti-aircraft weapons, etc. So when presented with the choice between the lives of civilians of an enemy state and the lives of your own boys in uniform, the government is obligated to choose the first. It has a responsibility to its own citizens and its allies that is more important than its responsibility to protect enemy civilians. If strategic bombing disrupts enemy war production and seriously disrupt the enemy's ability to wage war, it can be justifiable as a lesser of two evils.
Paul Tibbets and his crew members who flew on August 6, 1945, are American heroes, and rightly so, for ending the war that saved American lives, not killing enemy civilians. They do not deserve to be hated and bashed for something that actually worked and that's why non-Americans today took things for granted as an excuse to foster their hatred of Americans. Japan sowed the wind and reaped the whirlwind.