The U.S. had embargoed all oil exports to Japan before the Pearl Harbor attacks ever took place. They had frozen all Japanese assets in the United States in retaliation for the Japanese occupation of French Indo-China. Among other factors in the links below. (ex: U.S. President F.D.R. dislike of the Japanese people)
How U.S. Economic Warfare Provoked Japan's Attack on Pearl Harbor
http://www.independent.org/newsroom/article.asp?id=1930
Events leading to the attack on Pearl Harbor
https://en.wikipedia.org/wiki/Events_leading_to_the_attack_on_Pearl_Harbor
United States freezes Japanese assets
http://www.history.com/this-day-in-history/united-states-freezes-japanese-assetse
Those times were full of racism, I agree, but it wasn't one-sided. Typical tit-for-tat. Much of the media portrayal of Japanese people was very racist and was a behavior of the time. It was also a war driven, recruiting tool. Doesn't excuse it, but it was from both sides. The Japanese thought they were better and that others were cowards and lacked honor and dignity because of simple things like surrendering instead of committing suicide. As a result they treated POW's very harshly. The Japanese weren't that innocent as far as their mentality or actions.
The US didn't impose the embargo because it was looking for war. It did it because Japan was in the process of duplicating what Hitler was doing in Europe except in the Pacific theater. Japanese imperialistic ambitions were not just that, they were actually doing it and someone had to sanction them. Prior to the US embargo by 10 years, Japan had already invaded Manchuria. Then they moved into China, the Dutch East Indies etc. Can't turn a blind eye at Japanese atrocities, either. Look at what they did to the Burmese, Chinese and even Philippine people. How they treated POW's. Many Chinese still haven't forgiven them till today.
Ya DPRK is more trustworthy than the U.S.
The U.S. conducted it's first nuke test July 16, 1945 and not even a month later used a nuclear bomb on Japan on August 6, 1945.
North Korea conducted it's first nuke test in 2006 and eleven years later still hasn't used it on another sovereign country.
Far be it for me to advocate the use of nuclear weapons in any case other than a deterrent, but I think it's important to look at it in the context of how and why it was used. Before it got to the atomic bombs, the US bombed Japanese towns with incendiary bombs to show that it was coming and it was near and Japan needed to surrender. Nothing. Once the battle of Okinawa was fairly secured, Truman and Churchill issued the Postdam declaration giving Japan another chance to surrender. They mickey moused around that deal and never took it seriously. 70 cities (supposed industrial ones) were bombed by B-29's to show the Japanese it was time to give up, still they wouldn't. Japanese empire was willing to sacrifice its people. How can it not be held accountable? 110,000 Japanese soldiers were killed in Okinawa alone. Over 100,000 Japanese people were killed in the incendiary bombings of Tokyo yet the Japanese emperor wouldn't surrender to stop the massacre and destruction of his country and people. Where's the honor in that?
Japan attacked Pearl Harbor which is a military base killing a majority of military personnel. The U.S. attacked Japanese cities where civilians live, killing a majority of innocent men, women, and children. There is a big difference between a soldier and a civilian. Only a terrorist wouldn't differentiate between a soldier and a civilian.
After the attack on Pearl Harbor, the US fought the Japanese Navy and only the Japanese Navy for 4 years, ma man! The Coral Sea, the Battle of Midway along with Guadalcanal and New Guinea and the Soloman Islands. Saipan, Leyte Gulf and the Philippines then Iwo Jima and finally the last island before Japan proper in Okinawa. All these battles were only against the Japanese Imperial Navy and army and they still didn't show signs of surrender.
If the U.S. soldiers didn't want to fight the Japanese soldiers island by island then they shouldn't have signed up for the military or called a stalemate. The U.S. was willing to bomb Japan into extinction. The bombing of the innocent civilians of Hiroshima and Nagasaki is the greatest terrorist act of all time.
Stalemate? I don't think the military of any country that would've fought for that long and lost that many of its soldier's would think stalemate at that point. Just like Germany surrendered and a pact was reached by the victors that nothing like that would happen again, it was essential for the US and its allies to make sure that Japan would never have imperialistic ambitions again. Tough to sell a stalemate to any country in that position. You have an enemy at his knees and he won't surrender and you don't have any pressure on you, you go for the jugular. You also have to look at it in a sense that war is not a pleasant thing, and many innocent people get killed as a result. Japan, unfortunately chose that.
BTW, to put it in even greater context, the US and its allies suffered greater losses in the Pacific Theater than Japan; over 4 million military personnel deaths and over 25 million civilians combined as a result of the fighting to remove Japanese imperialism, while the Japanese and Axis participants suffered 2.8 million military deaths and a little over 1 million civilians despite the use of the 2 atomic bombs. I think it's safe to say that they still came out way ahead of the people they sought to conquer and rule.