It is heartening, and a little surprising, that the race to succeed Kofi Annan as UN secretary general was so hard fought. The job is grueling, requiring an extraordinary combination of public advocacy, tough management and tireless crisis diplomacy — and it can often feel thankless.

This week the Security Council picked Foreign Minister Ban Ki-moon of South Korea. Ban got a quick taste of his life to come, when the news of his selection was upstaged by North Korea’s announcement that it had tested a nuclear weapon. We wish Ban well. The UN is an essential organisation for promoting American foreign policy goals and for achieving a fairer and more peaceful world. Yet the past few years have seen many problems: the Security Council’s bitter divisions over Iraq to the scandalous behaviour of corrupt officials to the General Assembly’s watering down of reforms.

But the biggest problem has been the sometimes hostile, sometimes aloof, but never constructively supportive attitude of the Bush administration. The next secretary general cannot succeed without Washington’s active cooperation, or without pushing through the reforms that fell short in the previous term. The US strongly backed Ban’s candidacy. If it supports Ban in doing his job, it would increase his chances for success.