NORTH KOREA refuses to be bound by any global rules. Its hereditary dictator, Kim Jong Un, imposes forced labour on hundreds of thousands of his people and threatens to drench Seoul, the South’s capital, in “a sea of fire”. Nuclear weapons are central to his regime’s identity and survival. It has always been tempting for America and other countries to put North Korea’s nuclear ambitions on the back burner, in large part because of a chronic absence of good options for dealing with them. The history of unsuccessful responses to North Korea’s nuclear ambitions began in 1993, when Mr Kim’s father, Kim Jong Il, threatened to pull out of the nuclear Non-Proliferation Treaty (NPT) (see timeline above). So when in 2010 President Barack Obama made an impassioned plea for a world without nuclear weapons, there were grounds for optimism. Although Mr Obama has made progress in many areas, from non-proliferation deals with Russia and Iran, to international summits on nuclear security, his failure to stifle North Korea is glaring. Under his watch the country’s nuclear-weapons and missile programme has become steadily more alarming. It is now thought to have a stockpile of around 20 devices. Every six weeks or so it adds another.

This year the pace of ballistic missile testing has been unprecedented. Beginning with a fourth underground nuclear detonation in January (claimed by the regime to be an H-bomb, but more likely a souped-up A-bomb) followed by a number of tests of the technologies behind nuclear-armed missiles, Pyongyang carried out a fifth nuclear explosion on September 9th. The North now boasts that it can make a warhead small enough to fit on the Nodong, something American and South Korean officials were already convinced they could. These missiles can reach targets in Japan and South Korea, including American bases (see map above), and three improved versions were reportedly tested on September 5th splashing down in the sea west of Japan. There are also worrying signs of progress in the development of its longer-range missiles. Although three tests of an intermediate-range 4,000-kilometre (2,500-mile) Musadan missile failed in April, North Korean engineers learn from their mistakes, and further tests carried out in June were partially successful. Flight testing of the KN-08 intercontinental ballistic missile could begin soon and sometime during the second term of Mr Obama’s successor, these are likely to be able to strike New York. America needs worked-out plans to seize or destroy North Korea’s nuclear missiles before they can be used. China’s co-operation, or at least acquiescence, will be vital. So clear and present is the danger that even rivals who clash elsewhere in Asia must urgently find new ways to work together.

Dig deeper: For more on North Korea's nuclear threat, read our leader, A nuclear nightmare, and our Briefing, By the rockets’ red glare