As soon as North Korea threatened to test nuclear weapons, which I'm sure the Chinese adamantly told them not to say, the situation moved to a new level.
A total of three Field Army Groups (total 150,000 men) are now being deployed. According to PLA organization, one Field Army Group (YeZhan JunTuan) is equivalent to 50,000 men, consisting of 3 infantry divisions, 1 heavy-armor division and 1 artillery division.
Not a bad collection of hardware, just to seal a border. 9 infantry divisions, 3 armored divisions and 3 artillery divisions looks a lot more like the spearhead of an invasion force, though. The interesting detail here is a large offensive force is being prepared on an weak flank of an 'ally' who is sliding into conflict with a powerful enemy. Perhaps China has told North Korea that they're doing this in preperations to assist them. In Kim's world, he may even believe it.
Will the Chinese get in the ring to help out North Korea? Not a chance.
My money says that as soon as the DMZ goes hot, the Chinese will break through the western front, and race down as far south as they can. If they can sieze Pyongyang while we're still fighting it out on the border, they can 'overthrow' the government and provide 'peacekeepers' to stabilize the country with the same borders. Martial law under the PLA would keep the country from falling apart. It's very possible that the PLA could do a better job than we could.
The North Koreans do not regard Chinese as demons (Americans and South Koreans are). That may sound silly, but there would be far less panic and unrest if the Chinese stepped in to 'help'. Also, the PLA could essentially slaughter whoever did not obey until control was reestablished, which is not an option for the U.S. They could effectively if brutally keep the mess locked down long enough for international relief workers to bring in food, and start to establish order. Neither South Korea nor China wants the DPRK to shatter and explode; if they think they can control the situation, they will.
Although the Military Police is also under the PLA, replacing the border forces with those with combat capability has more implications than strengthening the border control. This is not only to prevent a sudden flood of N Korean refugees. The more important task is: a contingency plan for a possible American attack on N Korea.
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China has got to convey a message to Kim Jong-Il: Do not expect China to continue with the “Resist U.S. Aggression and Aid Korea (kangmei yuanchao)” policy from 1950-53. Today’s reality is: if a peaceful solution fails, Beijing will not send troops to N Korea to assist their fighting. Instead, they will send troops to close the border.
This gives away the suprise ending. The Chinese do not intend to stay on their side of the border and swat away refugees, nor do they intend to engage U.S. forces. That only leaves one reason to invade, and that's to take over, much like our good friend Uncle Joe Stalin did for half of Europe.
The overwhelming bulk of North Korea's combat power is on the DMZ. 24 hours into the war with us, the DPRK will be so badly disrupted and disoriented that they'll have no effective response against 100k+ troops kicking in the back door. Kim may even be so naiive as to allow them in without a shot. Either way, he's done for, and so is his regime. One way or another, China cannot tolerate half the U.S. military within a few days drive from Beijing, especially if they think we may have reason to be angry with them. If their only option is to invade a former ally to create a buffer zone, they will.
Kim Jong-Il is an uncontrollable nut case.
.....In Kim's world, he may even believe it.
What other options has he got? The PRC is his “only ally”.
.....Martial law under the PLA would keep the country from falling apart. It's very possible that the PLA could do a better job than we could.
True, they can do a much better job than the US.
.....They could effectively if brutally keep the mess locked down long enough for international relief workers to bring in food, and start to establish order. Neither South Korea nor China wants the DPRK to shatter and explode; if they think they can control the situation, they will.
If what you envisioned really happens, once the flighting starts and DPRK’s military begins to mobilize, I think the likelihood of a mutiny within DPRK’s armies would be very high. There won’t be too much fighting and bloodshed if Kim is assasinated in an early stage. It would still be North Korea but with a more pragmatic and open government. Call me wishful thinking but this is possible.
.....If their only option is to invade a former ally to create a buffer zone, they will.
Instead of calling it an “invasion”, PRC can always invent more than one excuses for the excursion into DPRK: 1) for PRC’s security reason, 2) for peace keeping reason, 3) for humantarian reason, 4) for restoring peace in the Korean Peninsula, etc.