The Chinese deny any offensive intent:
Chinese generals say they have no plans for military intervention in North Korea. Meanwhile, more Chinese troops are sent to the North Korean border each month, in anticipation of a political collapse across the border. That would bring a huge wave of refugees, and the growing army of Chinese soldiers are prepared to stop as many of the refugees as possible.
I would like to point out that having no intention to intervene in a North Korean civil collapse does not rule out Chinese forces entering North Korea.
Stopping North Korean refugees from flooding Manchuria would best be done in depth. And an in-depth defense would best begin 20 miles insides North Korea rather than starting the defensive effort right on the border and thus rendering 20 miles of Chinese territory the quarantine zone.
Oh, and I'm just guessing on the depth of the zone. I'm assuming that you'd want to make sure that refugees couldn't make the walk in one night of movement in order to hide from Chinese surveillance. Just being weak from hunger and moving through bad terrain--possibly with the elderly and surely with children will slow them down as it is. Forcing night moves will slow them more, giving Chinese security force more chances.
And it depends on how many refugees head north. If millions move would they swamp any effort that the Chinese mount?
Plus, if North Koreans know they can't flee the regime, will they be more likely to fight the regime? I know that many--including me--have some hope that a mass exodus of refugees will bring down the Bamboo Wall, but might bottling up the pressure cause an explosion?
