For a generation, the arc of international events has been mainly positive — the Cold War concluded, the Germanys reunited, apartheid is over. But a few conflicts refuse to end, and one became worse today as North Korea and South Korea exchanged artillery fire, killing two South Korean soldiers. It’s not yet clear how the incident began. Presumably the United States, which has substantial forces in South Korea, Japan and Guam, is at the moment watching closely.

South Korea is prosperous, reasonably free, a budding democracy, and supported by the most powerful government on earth. North Korea is impoverished, repressed and alone. Nearly all North Koreans would benefit immensely if the wall separating their country and South Korea was the world’s next wall to tumble. So why does the conflict between these two states refuse to end?

North Korea is the last truly closed society. The old Soviet Union, and then Mao’s China, were able to keep their populations cowed by blocking nearly all outside information, then depicting the larger world as a nightmarish place. Once Russians of the 1970s and 1980s, and Chinese of the 1970s and 1980s, knew what the larger world was like, the clock began to tick on their nations’  dictatorships. Today’s global information flow is far from ideal, but North Korea is the last nation in which the average person takes a big risk by trying to find out what’s happening in the world. This allows North Korea to be the last secret-police state, and means little internal pressure against its corrupt, paranoid autocracy.

North Korea needs endless conflict for its ruling family to stay in power. Both Germanys wanted their conflict to end. South Korea wants the Koreas conflict to end. The United States, Russian Federation, China and Japan want the Koreas conflict to end. Kim Jong-Il does not want the conflict to end — without it, he and his son would be tossed from power. Conflicts are hard to end when one major player (think Hamas) has a self-interest stake in endless misery for the many combined with power and riches for a few.

There was no Korean War treaty. A 1954 armistice stopped the shooting, but no peace treaty ever was signed. This is deceptively important. Even former dictatorships, such as imperial Japan, respected the peace treaties they signed: while international agreements including the 1975 Helsinki Accords, on human rights, helped begin to dissolve the old Soviet system. No peace treaty to tie the knot on the Korean War exists, and the belligerents have long since stopped trying for one. This means no liberalizing treaty requirements bind Pyongyang, while the fact that the state of war technically never closed helps Kim Il-sung, and now Kim Jong-Il, maintain an internal condition of xenophobia.