North Korea’s latest nuclear test is bad news, both for Northeast Asia and for a world that needs to reduce its reliance on nuclear weapons. But international overreaction – with responses that raise rather than lower the temperature, and push the region closer to a nuclear arms race – would make bad news even worse.

More than ever, it is China – and in particular Beijing’s new leader Xi Jinping – who holds the key to urging Pyongyang on to a new path