North Korea says it's tested a nuclear warhead (videos)

North Korea said it has hit the button on its fifth and potentially most powerful nuclear test Friday morning, claiming to have successfully detonated a nuclear warhead that could be mounted on ballistic rockets.

A few years ago there seemed some hope for the South Korea-initiated Sunshine Policy but this ended in 2007 and relations have vastly deteriorated since then.  North Korea is probably the least integrated economy in the world, and it's tempting to ignore them.  But yesterday's test proves that will be impossible.