Previous Republican administrations have named tough talkers, such as Daniel Patrick Moynihan and Jeane Kirkpatrick, to be ambassador to the United Nations. Nonetheless, George W. Bush's nomination of John Bolton to be his man in New York will give his partners around the world pause. Not only has Mr Bolton proved to be very abrasive as the State Department's chief arms controller over the past four years, but he is also an avowed unilateralist and long-standing critic of the UN. On the face of it, his appointment runs counter to the US president's apparent new stress, especially during his trip to Europe last month, on co-operative diplomacy in his second term.

Mr Bolton is hardly likely to re-invent himself as a born-again multilateralist. But if US policy were to be changed in that direction by the decision-makers in Washington, it would carry more weight with the UN's many critics on the Republican right if it came out of the mouth of Mr Bolton.

The appointment may well be a sop to the Republican right and to his patron, Dick Cheney, vice-president, in return for the nomination of more internationalist figures to top jobs in the State Department. Even so, the rest of the world will wonder why the price for letting Condoleezza Rice assemble a more coherent team in her State Department has to be paid at the UN.

For the wider world, the relevant issue posed by the Bolton nomination is whether it will spur UN reform. Clearly Washington believes it will further frighten the UN into fighting corruption and improving transparency. But Kofi Annan, UN secretary-general, has already set such moves in train, and the question that can be asked of Mr Bolton and the US administration is whether they will really want to build on internal UN improvements to give the world body a bigger role.

At present, for instance, Security Council plans to intervene in Darfur are blocked by disagreement over whether to pursue war criminals through the International Criminal Court, of which Mr Bolton is one of the administration's most diehard opponents. Nor is Mr Bolton's record on arms control exactly stellar, especially with regard to the nuclear weapons programmes of Iran and North Korea. Ironically, his reluctance to enter into direct negotiations with either country has left the US with the only option of taking these proliferation problems to the Security Council.

With his "proliferation security initiative", Mr Bolton has succeeded in getting many US allies to crack down on loose trade in nuclear materials. But this was more "a coalition of the willing" rather than the UN's regular multilateral machinery through which Mr Bolton, in his new job, must now wrestle. The dispatch of one of Washington's staunchest unilateralists to the UN may yet turn out an inspired decision. But the onus will be on Mr Bolton and his masters in Washington to prove this so.