China, North Korea and what happens after a nuclear test
Since the first nuclear test in 2007, there have been broadly two schools of thought amongst Chinese academics and commentators about the problem of the Democratic People's Republic of Korea (DPRK)'s nuclear programme.
The first regards it as a useful sideshow distracting the international community, causing serial headaches for the US and its allies, and diverting hostile diplomatic attention that might be directed towards China.
This is something that China broadly supports and manipulates for its own interests.
The second sees the actions of its ostensibly fellow Marxist-Leninist neighbour as those of a blackmailer of China, a huge liability, a place run by narcissistic leadership stuck in a time warp half a century behind the rest of the world.
The first assumes that China has real influence and power over North Korea and has some level of control of the situation there. The second suggests that it has far less.
With the suspected test of a hydrogen bomb by the DPRK on 5 January, can we see any evidence of which of the two views might be the more accurate description of what Chinese leaders themselves actually think?
There are some things we need to bear in mind when trying to answer this question. Chinese leader Xi Jinping has visited an astonishing 37 countries since becoming president in 2013 - but the DPRK has so far not been one of them.
The DPRK has reciprocated, with young leader Kim Jong-un not once taking the short, hour-long plane ride to Beijing since his elevation in 2011.
We also know that in the last 10 years, Chinese condemnation of the three previous nuclear tests has grown increasingly pointed and blunt.
The Beijing Ministry of Foreign Affairs this time curtly announced that it "strongly opposed" the DPRK's suspected testing of a hydrogen bomb. In 2012, it reportedly also stopped energy supply for three days after the last DPRK nuclear test.
Even something as seemingly trivial as the abrupt cancellation of performances by a visiting DPRK song and dance troupe to China late last year - because they were planning to sing songs celebrating Pyongyang's creation of a new powerful bomb - indicate Beijing's dim views.
Despite this, Chinese leaders do operate within clear constraints. The rhetoric they use towards the DPRK remains full of warm words affirming an alliance based on historic links and unshakable friendship.
This is for the simple reason that much as they regard the current regime in Pyongyang as bad, other options (a unified peninsula under South Korean, and therefore American, dominance, or, even worse, a failed, anarchic state with no governance at all) are worse.
It seems that while there might be some in Beijing (mostly in the think tank community and the more shrill, nationalist press) who believe China has some level of back channel control, all that we have learned in the last couple of days tends to support the idea that China's leaders believe their influence is limited, and their levels of frustration are high.
There is a bigger context for this. China's leaders currently have a lot on their plate.
The current downturn in the economy and the turmoil on the stock exchange in Shanghai, along with serious concerns about what sort of role they might need to play in the ongoing Middle East crisis (source of half of their petrol supply) and other geopolitical issues are more than enough to keep them busy.
Having yet one more problem in their neighbourhood demanding their time and attention is unlikely to be welcome. They could happily live without the drama of this test.
'Masters of blackmail'
The North Koreans are also driven by a similar distrust and wariness. For them, having a nuclear capacity grants them leverage as much over the Chinese as the Americans, their supposed chief enemy.
The great ancient Chinese philosopher Han Fei said two and a half thousand years ago that while people constantly prepare themselves to deal with their enemies, real calamity comes from those who they view as friends.
For the Chinese leaders, the North Koreans' "alliance" is a real and continuing burden, one that they cannot walk away from, but have no clear plan how to deal with.
So far, strangely enough, they have adopted the same tactics as America has under Obama, choosing simply to try to ignore the DPRK and sideline it. This week we have probably seen that tactic abruptly ended for both China and the US.
Like it or not, now Beijing will need to do something.
It might take the softer form of arranging a Xi presidential visit, or the harder one of placing real pressure on the US to restart the Six Party Talks, dormant since 2009.
If these happen, then Pyongyang will have shown once more that they remain masters of blackmail and manipulation of their vast, and seemingly powerful western neighbour, and that, more than any other country, they continue to show the limits of Beijing's diplomatic clout and influence.