I wrote that China would have a good route into North Korea while South Korea would have to slog across the DMZ, giving China an edge in reaching more terrain.
The Russians are working with the North Koreans on their small common border, too. I think the article I linked in the post above mentioned that, too.
Later I thought, wouldn't South Korea's industrial zone in North Korea have to have communications links that breach the DMZ?
Why yes it would:
The [Kaesŏng Industrial Park] is located ten kilometres (six miles) north of the Korean Demilitarized Zone, an hour's drive from Seoul, with direct road and rail access to South Korea.
So there you go. Securing that route will take a bit of time if North Korea resists, but it might not be more burdensome than North Korean resistance at the Yalu River bridge site on the main highway from China into North Korea.
I wonder how South Korea would use its marine corps in such a scenario?
Heck, that zone must be pretty familiar to South Korean intelligence by now. That would make it easier to set up a no-launch zone, too, in case North Korea starts bombarding Seoul.
The race is on. A partition of North Korea might take place one way or another, regardless of the existence of a pre-collapse understanding among North Korea's neighbors and America.