Why Beijing should lead on the North Korean crisis

"The definition of insanity is doing the same thing over and over again, but expecting different results."

The quotation is attributed to Albert Einstein but after a torrid few days on the Korean peninsula, it's one for Chinese leaders to ponder.

China is simply in the wrong place on North Korea. It is allowing Kim Jong-un's nuclear ambitions to undermine Chinese national interest.

There are complex reasons for this including history, habit and political culture. But among Chinese foreign policy experts and even on social media, unease is beginning to spread.

North Korea's nuclear programme has already driven South Korea to agree to the deployment of an American anti-missile system, locking Seoul deeper into a defensive triangle with Japan and the United States.

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Relations between Beijing and Seoul are at their worst in a quarter of a century and many South Koreans have been alienated by unofficial Chinese sanctions against the whole spectrum of South Korean interests from supermarkets to boy bands.

This is good for North Korea but for no-one else. It is nonsensical for China to punish South Korea for trying to defend itself against a nuclear threat which even Beijing describes as real and urgent.

And if North Korea continues its drive for nuclear weapons, there may be a worse arms race to come. A nuclear-armed Japan would hardly be in China's national interest.

But despite this catalogue of warning signals and failures, China seems trapped in an unfinished history marked by binary choice: a nuclear-armed North Korea or a reunified Korea with American troops on China's border. Between these choices, it finds a nuclear-armed North Korea preferable. But if it thinks hard enough, perhaps there is an alternative.