North Korea's detonation of a nuclear test weapon is a profoundly retrogressive event in world politics. It challenges existing non-proliferation policies and signifies that they have failed in this crucial case. Henceforth international pressure on the isolated Stalinist state will have to accept that it has become the ninth member of the nuclear club, despite its people's desperate poverty and need for aid.
The test gives North Korea extra leverage in future talks or in response to threats of military retaliation. But it still remains just as difficult as before to decide whether this is a rationale to strengthen its hand in bargaining on whether to abandon its nuclear weapons, or an aggressive signal that it has no intention of doing so.
Yesterday's reactions from North Korea's neighbours and interlocutors vividly illustrate this political conundrum. The Chinese government described it as a "brazen" breach of international norms, language usually reserved for hostile states. Since China is regarded as its closest associate, having resisted military pressure and encouraged a multilateral approach, this shift presages a tougher policy at the United Nations Security Council. South Korea, which has also pursued an accommodating policy towards Pyongyang, was similarly hostile. Both of these states fear the consequences of North Korea disintegrating, which would leave them having to absorb millions of refugees. Alternatively, they would be frontally exposed to an escalating military confrontation.
Japan is also deeply and rightly concerned. Its new prime minister, Mr Shinzo Abe, on timely visits to Beijing and Seoul over the weekend, made it clear that his country's commitment to a non-nuclear policy will not change. This threat will be a spur to his efforts to improve relations with China and South Korea, but he is bound to face new right-wing demands at home to change Japan's stance.
The United States is the key player in this drama and must bear much of the blame for this failure. The US's recent engagement with Pyongyang involved a far-reaching policy of incentives to switch its nuclear programme towards a non-military technology under the Clinton administration. The Bush administration abandoned that approach and put North Korea on its list of the most dangerous states in the world. This provoked its rulers to withdraw from the Non-Proliferation Treaty three years ago. President Bush refused to talk directly to the North Koreans to reassure them they were not under any threat of nuclear attack. By joining the multilateral talks favoured by China and South Korea he seemed to favour an alternative diplomatic approach.
This test concludes North Korea's disenchantment with that policy, which was signalled by its withdrawal from those talks last year and the severe impact of economic sanctions. The UN Security Council has no option but to respond firmly and strongly to this provocative act. But it must still hold open the possibility of a negotiated solution.