South Korea and the United States have updated their disaster plan, in the event of a collapse of the government in North Korea. The new Operational Plan 5029 lays out who (between U.S. and South Korean forces) will do what if things go south in the north. The new plan calls for the United States to mainly take care of securing North Korean nuclear weapons, while the South Korean will deal with refugees, and sending forces north to restore order. The details of the plan are classified, so it is not known what role China is expected to play. China is believed to have its own plan for this chaos, and it might involve Chinese troops going in to make sure a communist government comes out of it all. China does not want North Korea absorbed into South Korea, although most Koreans would prefer a united Korea. China does not want a prosperous democracy on its border.
But a united Korea is not universally popular in the south. South Koreans sees the collapse of the North Korean government as a catastrophe for itself, economically and culturally. That's because of the grim experience it has had so far with North Koreans who have managed to escape the harsh police state to the north.
In the last twenty years, over 100,000 desperate refugees have managed to get out of North Korea. Most are still in China, where nearly all the refugees go initially. That's because of the long 1,386 kilometers) border with China, which is demarcated by rivers, not a heavily fortified and mined DMZ (the five kilometer wide Demilitarized Zone that separates North and South Korea). Four years ago, China began building barbed wire fences along portions of its North Korean border most frequently used by refugees, and smugglers. Both are bothersome to China, if only because they increase the crime rate on their side of the border.
Many of the current North Korean refugees want to reach South Korea, where they are guaranteed asylum and financial support. This means travelling through China to a third country, then arranging transport to South Korea. There are smugglers, some of them provided by NGOs or religious groups, who specialize in this sort of thing.
Currently, there are over 16,000 North Korean refugees living in South Korea. Over 70 percent of them are unemployed, through a combination of culture shock and lack of useful skills. North Korea is run like a prison, with initiative and innovation (useful skills in South Koreas market economy) considered criminal behavior. The South Koreans were appalled when they began to note how widespread these habits were up north. Apparently many North Koreans have gotten the word as well. While more North Koreans are reaching South Korea (2,544 last year, versus about 500 a year in the late 1980s), most of them (78 percent last year) are women. Two decades ago, less than ten percent of those reaching South Korea were women. The women are more adaptable, and have an easier time finding a spouse. For the North Korean men, South Korean society is actually quite hostile. Moreover, men are more closely watched in North Korea.
Northerners are regarded as damaged goods in the south, and stand out by the way they walk (with a bit of fear in their step) and how they talk (the northern accent is easy to recognize and hard to lose). But the worst problem for northerners is living in a society where your every move is not dictated by some government official. It's been very difficult for the refugees to overcome these cultural constraints and fit in, or even just get a job. So most of the refugees are unemployed and basically living on the dole.
If the North Korean government were to collapse, South Korea would be honor bound to do something. To further complicate matters, China does not want North Korea merged into a democratic South Korea. But if the government collapses in North Korea, China will either have to occupy the place (which might result in fighting armed, and angry, North Koreans who would rather unite with their prosperous brothers in the south.) Whatever happens, the vile culture that has developed by over 60 years of communist police state rule in the north, is going to be an expensive problem for someone to clean up.