why would china protect country like that ..You mean like Mussolini? Hung upside down by the people and beaten to a pulp? Who knows ... the situation seems to be pretty complicated, so it might take decades or centuries even until the government there changes.
China is North Korea's protective power and the USA would risk war with China. Also, North Korea's army is the world's 4th largest (and probably well equipped too ... at the expense of the people).
Also, North Korea possesses long range missiles capable of transporting nuclear bombs to every spot in the USA.
Meanwhile, the US nuclear arsenal is rusting away in its bunkers. I've heard somewhere they're probably not properly maintained b/c that would cost billions.
So, if there was a war between North Korea and the USA, especially when China is involved, then chances are that the USA would not only be destroyed but also be conquered afterwards. US citizens would have to learn Chinese, probably.
Yes, there's still a lot of injustice in this world.
If I had the (alien or very advanced) technology, I would transport all military in the world to a planet far away, where they have a cozy place full of flowers and rainbows, and all that would happen within the same millisecond, so no-one would have time to object.
and lol at your idea .. no we should transport to that planet and let them bomb each other