1) Hey North Korea! China thinks you're a bunch of dorks!
North Korea's leadership is notoriously petty when it comes to their reputation. (Really? A dictator of small stature with a bouffant hairdo is vain?) The public revelations that their greatest (only?) ally considers them childish headache could make the North think twice about future provocations. Though China's official line is unlikely to change, this betrayal of true sentiment must make North Korean leadership do a gut check.
Additionally, these revelations could very well add fuel to any fires of insubordination among ruling North Korean elites. While it's a stretch to assume anything about the hermit kingdom, let's say that high-ranking officials in the DPRK government have access to these cables. The language of these cables explicitly underscores North Korean weakness. Those party members chafing under the recent reorganization of DPRK power might find enough validation in the cables to motivate them to more rebellious positions. Dare we say that these cables might actually bring about the collapse of Kim Jong-il's regime? It wouldn't be surprising (although causality would be impossible to prove) but that doesn't mean it wouldn't be bloody.
2) North Korea is hemorrhaging not only its population but also its leadership.
This is particularly embarrassing for the North. While the quantities of refugees from the North could be blamed on famine, the defection of North Korean diplomats represents a particularly black eye. These are the lucky members of society, those who have made it to the top. If the landed elite are abandoning the country, what does that say about the society? Refugees from famine are sign enough of weakness but privileged defectors are damning. As with the news about China's honest appraisal of the North, should this information reach disgruntled members of the DPRK's ruling party it might be enough to push them to action.
3) US and ROK diplomats believe Kim Jong-un doesn't stand a chance.
Kim Jong-il is sick and on his way out the door. Kim Jong-un is young and inexperienced. Kim Jong-il had to weather 3 separate insurrection attempts during the 90's and he had the benefit of 20 years of experience as a party heavy-weight before assuming the throne vacated by his father. Kim Jong-un is a mid-20's 4 star general with no military experience. The wolves are circling, just waiting for the death of the old man before taking over the party.
Can you imagine how Kim Jong-un is going to feel if he gets his hands on that?
Conclusions:
While North Korea has shown every sign that it is a rational (if not downright shrewd) international actor, these cables threaten to disrupt the ruling members who make up this group. And these ruling members have shown every sign that they are petty (if not downright insecure) leaders. So how do we think the various players will react to these cables? Let's break them down point by point. For the sake of simplicity we can divide the leaders into two groups: pro-status quo and pro-regime change.
- China thinks North Korea is an annoying l'il bitch:
PRC: What!? These leaders are idiots!
PRC: Oh come on! These guys gotta go.
PRC: Goddamned right. You're going down you bastards.
- North Korean is losing everyone:
PRC: Oh come on! These guys gotta go.
- Kim Jong-un is going to fold like a house of cards:
PRC: Goddamned right. You're going down you bastards.
So what is most likely to happen really? (Again, assuming that the leadership in North Korea has access to these cables.) Sensing that the game is almost up, I'll bet North Korean leadership gets REALLY aggressive. It might be deterred somewhat by China's transparent frustration but the pro-status quo leadership (mainly Jong-un) will attempt even harder to cement his position of leadership internally. Until he feels comfortable about his position, I'm guessing exogenous threats from China, South Korea, and the US will come secondary.