The situation in North Korea defies any simple solutions. I have met North Korean defectors. They are definitely telling the truth. I am also quite familiar with North Korea as seen with Google Earth and other space imaging- they are quite visible on declassified satellite imagery going back to the 1970s. (They were far bigger then than now) What are we to do? I don't know, but one thing would help a great deal which is in our control, we should close Guantanamo Bay and all similar facilities, and stop "rendition" and all secret jails. We also should repudiate "first use" of nuclear weapons.
And all Americans should take some quality time to watch the many hours of defector testimony from the 2013 UN Commission of inquiry, visible on the UN web site. This is an exhausting experience but once you do that, you will know far more about the situation there than you would learn from any book. Please consider watching these videos -
A good source of information on current North Korean news with an appropriate balance of human rights issues is the English language part of http://dailynk.com
The political situation in South Korea has to be understood in the context of the postwar period when both North and South Korea's governments were in a race to see who could be most repressive. Since many South Koreans were familiar with their own governments brutal repression, they became less aware than they should have been of the even worse repression going on in the North.
Its a similar situation in the US. We should be careful that we dont buy into the natural but in this case quite wrong assumption that if Bush (and now Obama) condemns them they are probably not as bad as we say. In reality, they are worse than we say. It has always been that way. I dont know how else to put it. Not only are they horrible, but you can actually follow the defector stories and see the places they are talking about on Google Earth. Sometimes you can even see individuals, for example, walking in the snow, when the sun creates a long shadow.
When the borders open and the carnage of the last 70 years finally sees the light of day, the world will be shocked beyond the ability of words to explain.