Don't Run, We Are Your Friends Dept.

I've followed news reports in the past about the underground railroad that exists in North Korea to aid escape to China or other countries. If you want to ride that particular railroad, you'll need money or some other way to bribe your way out — and there's always the chance that you'll get caught.

Any government that refuses to allow its citizens freedom of egress, on pain of a bullet in the back of the head, is clearly worried about something.