Kim Jong Un, the mercurial leader of North Korea, has suddenly announced that his nation will cease any efforts at reconciliation with South Korea. Given the 80-year separation of the peninsula and the fact that the two nations are still technically at war, this may not seem a big deal. But for South Koreans and their allies it is huge and troubling development.

Kim has indicated he will order a rewrite of North Korea’s constitution to eliminate any possibility of unity with the south. Previously, the stated policies of both North and South Korea were to work toward reunification, and it was to some extent sincere.