Even by its own aggressive standards, North Korea’s actions over the past couple of weeks have been extraordinary. Kim Jong-un, the country’s young dictator, has threatened the US with nuclear Armageddon, promising to rain missiles on mainland America and military bases in Hawaii and Guam, and declared a “state of war” with South Korea. Kim Jong-un announced that he would restart a plutonium-producing reactor at its Yongbyon nuclear site, while enriching uranium to build more nuclear weapons, and barred South Korean managers from entering the Kaesong industrial complex, almost the only instance of North-South co-operation. All this comes after the regime set off a nuclear test, its third, in February. Tensions are the worst on the peninsula since 1994, when North Korea and America were a hair’s breadth from war. The US has tried to play down the aggression, talking of a “disconnect between rhetoric and action”, and some parts are pure bluster. The nuclear threat against mainland America is patently hollow. It will be years before the North has the technology to dispatch nuclear-tipped missiles. In response to North Korea’s dire threats, the US deployed of B-2 stealth bombers and F-22 fighters. Now more than ever, America needs to cajole China to press for change in its satellite. Apart from humanitarian aid to the North’s stunted people, all other commercial favours towards the regime should be stopped. Sick of Mr Kim and his family racket, China signed up to fresh UN financial sanctions against North Korea after the latest nuclear test. China has the capacity to choke the most iniquitous sources of the criminal regime’s cash.