What I Saw in North Korea and Why it Matters (Siegfried S. Hecker)
Siegfried Hecker ran Los Alamos labs and has traveled in North Korea as a civilian observer. A fascinating look at North Korea.
If you want more than a sound bite treatment of the North Korean situation and history this is an excellent video. It also includes an overview of the difference between Plutonium and Enriched Uranium in nuclear bombs (9:30) that's important to understand when talking about nuclear proliferation.