Leading article: North Korea shows why new international rules are needed

A few hours after Nato concluded its summit in Strasbourg and a few hours before President Obama began his speech on nuclear risks in Prague, North Korea launched the rocket that had been moved into position the previous week. It was the ultimate act of attention-seeking from a country which has remained stubbornly aloof from the general thaw in international relations that followed the departure of George Bush. It was also, as Mr Obama and many other leaders immediately pointed out, irresponsible and extremely dangerous. The UN Security Council was due to meet in emergency session last night.

In the event, North Korea's belligerent statement was more in the intent than in the result. Whether the purpose was, as Pyongyang insisted, to launch a satellite, or – as many Western military experts agreed – to test a rocket capable of launching a long-range missile, the attempt failed. The US military reported that two stages of the rocket and its payload had fallen into the Pacific. Some 11 years after it first tried to launch a satellite, it appears, North Korea has still not mastered the technology. This is the good news. The bad news, of course, is that a rocket that misfires is every bit as dangerous as one whose trajectory is controlled.

None of which should disguise the fact that the signal North Korea and its reclusive leader, Kim Jong-il, wanted to send was at once hostile and defiant. As such, it provided the perfect illustration of the arguments the US President was about to make half a world away. In his address in Prague, Mr Obama called for a global summit on nuclear security and for new partnerships to prevent the spread of nuclear weapons. He said he wanted a new treaty to end the production of fissile materials and – though this was probably not feasible in his lifetime – a world free of such weapons altogether.

In some ways, Mr Obama's language and vision represented a return to an earlier view of the world – a world before 9/11, where the nuclear threat had not yet been superseded by the "war on terror". His decision to make arms control, and sharp mutual reductions in numbers of nuclear warheads, the centrepiece of a new relationship with Russia is in the same, seemingly old-fashioned, vein.

Old-fashioned, though, does not mean wrong. While there is a point at which terrorism and nuclear proliferation coincide – in the risk that a terrorist group could one day acquire a nuclear weapon – this danger increases in proportion to the amount of unregulated nuclear activity in the world. The priority must be to bring all states that possess, or aspire to, a nuclear capability into a modern regulatory framework that is more consistent and enforceable than the non-proliferation regime that obtains today.

The problem with trying to negotiate such a framework, however, is that the words of existing nuclear powers often ring hollow. When Mr Obama warned North Korea yesterday that it "must know that the path to security and respect will never come through threats and illegal weapons", he was repeating a truism that has proved completely wrong. North Korea knows – from the example of India, Pakistan and the West's concerns about Iran – that a nuclear capability is a sure-fire way of being taken seriously. Mr Obama was far more convincing when he said his administration would work to bring the Comprehensive Test Ban Treaty into force, which neither the US nor China has yet ratified. That would indeed be a good place to start.