North Korean nuclear crisis explodes There can be little doubt that the nuclear test undertaken by North Korea yesterday represented a significant escalation in its long-running stand-off with the outside world. Coming soon after Pyongyang successfully fired an advanced three-stage version of its Nodong rocket system, with the range to hit the west coast of the US, the detonation of a device with an estimated yield of seven kilotons - just under half the power of the bomb dropped on Hiroshima at the end of the Second World War - suggests North Korea is closing in on its ambition of acquiring a home-grown nuclear arsenal. The concept of "Songun" - Military First - remains deeply rooted in the North Korean psyche, even if it means allowing millions of the country's citizens to die of starvation, which is what occurred in the Nineties when the national economy collapsed. Nor has there been any shift in this confrontational policy since Kim Jong-un succeeded his father as Supreme Leader in 2011. The disturbing advances in the nuclear programme have taken place on his watch. Western attempts to bring Pyongyang to its senses have clearly made little headway, which is why the only realistic opportunity of heading off a potentially disastrous confrontation lies with China, North Korea's communist supporter and largest trading partner. Chinese officials frequently complain that they exert little influence over their delinquent neighbour, but these claims are disingenuous. North Korea could not survive without Chinese support, and the fact that Kim Jong-un's succession was decided in Beijing, rather than Pyongyang, tells its own story. The crisis in North Korea is now too serious for China to continue to turn a blind eye. Beijing should accept that a nuclear-armed Pyongyang is as much a danger to the Chinese as it is to the rest of the world.