The helicopters are taking off and landing now in the tsunami-shattered villages and towns. The sick are being taken for treatment. Clean water is being delivered. Food is arriving. Soon the work of reconstruction will begin.

The countries doing this good work have politely agreed to acknowledge the “coordinating” role of the United Nations. But it is hard to see how precisely the rescue work would be affected if the U.N.’s officials all stayed in New York – or indeed if the U.N. did not exist at all.

The U.N. describes its role in South Asia as one of “assessment” and “coordination.” Even this, however, seems to many to be a role unnecessary to the plot. The Daily Telegraph last week described the frustration of in-country U.N. officials who found they had nothing to do as the Americans, Australians, Indonesians, and Malaysians flew missions.

It will be the treasury departments of the G-7 missions that make decisions on debt relief, and the World Bank, aid donor nations, private corporations, and of course the local governments themselves that take the lead on long-term reconstruction. And yet we are constantly told that the U.N.’s involvement is indispensable to the success of the whole undertaking. How can that be?

In a notable interview on December 31, Clare Short, the former international development secretary, explained that the U.N. possessed a unique “moral authority,” and without this authority, the relief effort would be in trouble because…well, after that it gets hazy.

It is obviously not because of the U.N. that countries like Britain, America, Germany, Japan, Australia, and India are donating so generously to the countries in need. Nor, even more obviously, is it because of the U.N. that the afflicted countries are accepting aid. Nor again has the so-called authority of the U.N. induced Burma to accept any aid that Burma’s rulers find politically threatening.

Nor finally is the U.N. really quite so hugely popular as supporters such as Ms. Short would wish it believed. The Pew Charitable Trusts – the same group that conducts those surveys on anti-Americanism worldwide – reports that the U.N. carries much more weight in Europe than it does in, say, the Muslim world. Only 35% of Pakistanis express a positive attitude to the U.N., as do just 25% of Moroccans, and but 21% of Jordanians.

The U.N.’s authority is instead one of those ineffable mystical mysteries. The authority’s existence cannot be perceived by the senses and exerts no influence on the events of this world. Even the authority’s most devout hierophants retain the right to disavow that authority at whim, as Ms. Short herself disavowed its resolutions on Iraq. And yet at other times those same hierophants praise this same imperceptible, inconsequential, and intermittently binding authority as the best hope for a just and peaceful world. An early church father is supposed to have said of the story of the resurrection: “I believe it because it is absurd.” The same could much more justly be said of the doctrine of the U.N.’s moral authority.

Whence exactly does this moral authority emanate? How did the U.N. get it? Did it earn it by championing liberty, justice, and other high ideals? That seems a strange thing to say about a body that voted in 2003 to award the chair of its commission on human rights to Muammar Gaddafi’s Libya.

Did it earn it by the efficacy of its aid work? On the contrary, the U.N.’s efforts in Iraq have led to the largest financial scandal in the organization’s history: As much as $20 billion unaccounted for in oil-for-food funds. U.N. aid efforts in the Congo have been besmirched by allegations of sexual abuse of children; in the Balkans, by charges of sex trafficking.

Is the U.N. a defender of the weak against aggression by the powerful? Not exactly. Two of this planet’s most intractable conflicts pit small democracies against vastly more populous neighboring states. In both cases, the U.N. treats the democracies – Israel, Taiwan – like pariahs.

This record may explain why the U.N. is regarded by so many Americans as neither moral nor authoritative – and why American leaders of both political parties reject U.N. attempts to control American actions.

And indeed, when we talk about U.N. authority, it is U.N. authority over America that we always seem to have in mind. The U.N. is the stated topic, but it is American power that is the real subject of concern.

As Ms. Short complained in the Independent on January 1: “At a time when the world faces terrible challenges, of poverty, disorder, and environmental degradation, there is a real danger that the U.S. government is consistently undermining the only legitimate system of international co-operation that we have.” In a world that contains – among others – the E.U., NATO, the World Trade Organization, and literally hundreds of regional and global governmental and nongovernmental associations, it seems bizarre to describe the U.N. as the sole legitimate international actor.

But of course the U.N. is the only one of these actors consistently to come into conflict with America. It is this bias of the U.N. system – and not any of the U.N.’s meager list of achievements – that causes so many on the global left to regard it as legitimate in a way that they do not regard, say, international treaties for the protection of patents.

Europeans often interpret American skepticism about the U.N. as a sign of American indifference to world opinion. Yet Americans care passionately for the good opinion of the world. Nothing John Kerry said during the 2004 campaign inflicted as much damage to the president as his charges that he had ruptured alliances and lowered America’s standing in the world.

Unlike many on the European left, however, Americans seem able to remember that the U.N. is a means to an end, not an end in itself.

Americans see the U.N. not as an ineffable mystery, but as an institution invented six decades ago by human beings no wiser than their modern successors to respond to the problems of their time – which were not the same as the problems of ours.

If the U.N. keeps failing, the answer is not to ignore its faults, but to reform or replace it. There is growing interest in some American quarters in the idea of a new international association, open only to countries that elect their leaders democratically. At a minimum, Americans expect transparency, accountability, and some greater approach to evenhandedness in the Middle East. But the real challenge to all of us, in all the democracies, is this: to be guided by realities, not fantasies – and especially not such uniquely unconvincing fantasies as the allegedly unique moral authority of the United Nations.

Mr. Frum is a former speech-writer for President Bush and a resident fellow at the American Enterprise Institute. He is the author with Richard Perle of “An End to Evil: How to Win the War on Terror.”