For the second time in four months Kim Jong Un has dared to humiliate Chinese president Xi Jinping, the one foreign leader with the power to strangle North Korea’s economy with potentially fatal effects for the Pyongyang regime.
Mr Kim not only conducted a nuclear test on Sunday knowing that it would enrage Beijing; he did so as his Chinese counterpart was preparing to receive the heads of Brazil, Russia, India and South Africa in the coastal city of Xiamen.
The test set off a magnitude 6.3 quake that shook the ground in Yanbian, an area in China’s Jilin province near the North Korean border. On Sunday night China’s environment ministry said it would be monitoring border areas for radioactive fallout.