The United States of America is the only nation in the history of mankind to use nuclear weapons in an act of warfare. The occasion was at the end of World War II. The ultimate victory by the Allied forces was assured. The only question was whether Japan could be defeated without massive loss of Allied lives in a final assault on the Japanese homeland. The Japanese soldiers were known to be fanatical defenders of occupied islands, and no one doubted that fanatical resistance of the homeland would be costly for Allied forces, even though ultimate victory was never in doubt.
So, the Americans chose terrorism as their strategy. The atomic bomb program was a top secret effort, begun to ensure that America obtained the atomic weapon before Nazi Germany could do so. The Germans, however, never were able to carry out a serious effort to produce an atomic bomb, and Germany was defeated by conventional warfare. There is no evidence that serious thought was ever given to use of the atomic bomb on Aryan Germany, and the rush to get to Berlin ahead of the Russians assured that great haste was made by all available Allied American/British forces to rush towards final victory.
Would Japan have been bombed with the atomic bomb if it had been populated by Caucasian peoples?
No one can say for sure, but a reasonable argument can be made that America would never have bombed a Caucasian nation in the manner that it bombed Japan with atomic weapons. Regardless of racial issues, one thing is for sure. America used the atomic bomb as a terrorist weapon, quite deliberately. The historic record is very clear that the U.S. government decided to bomb population centers in Japan with atomic weapons in order to terrorize the population and the government into surrendering, so that American troop losses would be minimalized in obtaining the final victory. The plan was to continue dropping atomic bombs on Japanese cities until the people capitulated. It took two bombs for surrender to be agreed to by the Japanese. The terrorism strategy worked!
In the decades since World War II, more nations have developed nuclear weapons, and the advanced nuclear nations have stockpiled sophisticated thermonuclear weapons, tactical atomic weapons, atomic artillery, atomic suitcase bombs, and all sorts of very dangerous weapons. Despite close calls in Korea and other near exchanges during the "Cold War", atomic weapons have never again been used in warfare.
The United States, along with other nations, has attempted to prevent nuclear proliferation; that is, the U.S. has tried to prevent other nations and organizations from obtaining nuclear weapons, and has even threatened war (or preemptive attacks) in order to prevent nations from obtaining nuclear weapons.
Does the U.S. have some sort of "moral authority" in its desire to prevent nations such as Iran and North Korea, or Libya or Iraq from obtaining nuclear weapons?
Clearly, the U.S. has no such moral authority. As noted above, the U.S. is the only nation ever to use atomic weapons in warfare. The U.S. has continued to develop nuclear weapons and has repeatedly threatened to use them to "protect" U.S. interests, even preemptively. The U.S. has used depleted uranium in warfare, which has resulted in hundreds of tons of radioactive material (with radioactive life of 4.5 billion years) polluting Iraq and other nations subjected to attack by U.S. forces. The U.S. has illegally used cluster bombs against populated areas, another moral and legal failure. The U.S. has refused to sign land mine treaties, and has continued to deploy land mines in its military activities — another moral failure. The U.S. has waged war against civilian infrastructures, resulting in immoral suffering of many hundreds of thousands of victims. The U.S. has armed tyrants, supported despots, sold munitions to countless terrorist armies of suppression, and even used its own military illegally against its own civilian populations at Pine Ridge, Ruby Ridge, and Waco.
The U.S. has no moral authority whatsoever. But the U.S. does have a military philosophy and a history of making every effort to prevent rival nations from having power to challenge U.S. interests. A phrase in vogue now in U.S. geopolitical strategy is called "full spectrum dominance". The U.S. wants to prevent other nations from having power to even considering challenging U.S. policies or aggressions. The U.S. concept of "Pax Americana" requires U.S. military adventurism and occupations of foreign nations, including those of Central Asia, the Persian Gulf, and any part of the planet where U.S. economic interests are subject to challenge by economic competitors.
The U.S. wants to be able to wage war with impunity. The U.S. wants to be able to defeat its foes and potential foes with little effort, and with little fear of loss.
If Iran or North Korea or Libya or Iraq had nuclear weapons, could they defeat the U.S. in battle? Would a "terrorist" attack against the U.S. mainland, using a nuclear weapon or another weapon of mass destruction defeat the U.S. and bring it down militarily? Absolutely not! If terrorists or a foreign nation used an atomic weapon to destroy an American city, the American military would be able to use technology to detect the source of the weapon, and instant retaliation against the attacker would be assured, and it would be massive — disproportionate. If a foreign nation attacked the U.S. with ten megatons of TNT, the retaliation by the U.S. would be many times more powerful. The U.S. would not "lose" a war with such a nuclear exchange.
But, the U.S. economy would be severely affected. Despite the awesome military power possessed by the U.S., the U.S. public would be dominated by fear in the event of any attack against the U.S. homeland by weapons of mass destruction. The U.S. economy would be devastated, and even a temporary shutdown of the U.S. economy would have a catastrophic impact on the portfolios of the ultra wealthy American who possess a highly disproportionate amount of the total wealth of America. The Super Rich of America would suffer the most in a nuclear attack and it is for the Super Rich Americans and American corporations that American policy is set.
Thus, the U.S. sets its policies to prevent additional nations from possessing nuclear weapons. Interestingly, nations such as Pakistan and India possess these weapons, but since both nations are disinclined to attack America, their possession of nuclear weapons is not a huge concern. If India and Pakistan attacked each other with nuclear weapons, the American government would be far less concerned than if either or both nations became antagonistic towards America.
Nations around the world have seen the new aggressiveness of America, and the observation of how the U.S. treats nations with perceived ability to defend themselves with weapons of mass destruction compared with weaker nations. The U.S. attacked Iraq, after using U.N. sanctions to guarantee the elimination of Iraq’s former WPD arsenal, whereas the U.S. has pursued a much more circumspect policy towards North Korea.
One thing is for sure, if the U.S. can dominate other nations, it will. If the U.S. can intimidate other nations, it will. If the U.S. can wage war with minimal cost and loss in order to protect or benefit American corporate interests, it will.
Other nations see this and increasingly want to protect themselves. North Korea is now insulting U.S. officials, such as Donald Rumsfeld. Would North Korea be able to do this without nuclear weapons?