Calling for reform is one thing; agreeing on the details is quite another. The United States, Britain and other wealthy Western countries tend to see the UN as an inefficient bureaucratic behemoth that encourages corruption and waste when it is not providing a forum for the spewing of anti-Western rhetoric. The West's message to the UN can be summed up as: "Do more useful things and charge us less."
For the smaller and poorer countries that make up the majority of the world's states, however, the UN's problems appear in a rather different light. Their biggest complaint is that the five permanent Security Council members - Britain, China, France, Russia and the US - use their elevated status to order the planet's affairs in their own interests. "The Security Council can no longer be maintained like the sanctuary of the holy of holies, with only the original members acting as high priests deciding on issues for the rest of the world," President Frederick Chiluba of Zambia told his fellow leaders on Sunday.
Does the answer lie, then, in a slimmed-down, corruption-free UN equipped with the latest techniques of Western business management, or does it lie in adding Brazil, Nigeria, India, Indonesia and others to the Security Council? By general consent, reforms are necessary across the whole spectrum of UN activities, from the council itself to various obscure agencies and programmes whose sell-by date has long since passed.
Prescribing a cure for the UN's ills is no simple matter, for it all depends on what the UN is or should be, and on that point the organisation's member states have never been and are never likely to be in complete agreement. The UN is not a world government, nor even a fire brigade zooming from trouble spot to trouble spot to extinguish conflagrations. Yet it is clearly something more than the world's biggest talking shop or statistics-gathering agency.
The UN has no independent military forces and has seemed for years to be on the brink of bankruptcy, yet the world expects it to be a problem- solver. Hence it tends to attract the blame when humanitarian or peace- keeping operations conducted under UN auspices are inadequate, as recently in Somalia, Rwanda and Bosnia. Governments find it convenient to criticise the UN as if it were a sovereign policy-making institution, when in reality the failures are of their own making.
The truth, understood perfectly well by every government but rarely acknowledged in public, is that the UN can take action only when its member states let it. Sometimes they want it to keep well out of the way. Often, when they do let the UN in, they restrict its mandate or fail to supply it with the necessary resources. At all times, the UN is nothing more or less than a mirror image of the positive and negative qualities of national governments themselves.
The most dramatic illustration of the UN's limitations occurred in 1962, when John F Kennedy and Nikita Khrushchev overcame the Cuban missile crisis - perhaps the most dangerous moment in human history - by direct negotiation rather than by turning to the UN. On the other hand, the US has twice found the UN a valuable means of mobilising international support for a war: in Korea in 1950-53, and again in Iraq in 1990-91. Few countries going to war make the mistake these days of neglecting to prepare a case for presentation at the UN.
The perception of the UN as a cumbersome institution incapable of rising to the world's security challenges owes much to unrealistically high expectations that were placed on it after the end of the Cold War. In the era of US- Soviet confrontation, superpower rivalry frequently paralysed the UN, but by the end of the Eighties the decline in world tensions was permitting the UN to notch up successes in places as far-flung as the western Sahara, Namibia, Afghanistan and Cambodia.
When George Bush skilfully used the UN to put together an international coalition to end Iraq's occupation of Kuwait in 1991, the UN's prestige stood at its highest point in the post-Communist age. Yet this prestige reflected a degree of international harmony and hope for a better world that was rapidly to diminish as murderous conflicts broke out in former Yugoslavia and Rwanda.
The deployment of UN peace-keeping troops in former Yugoslavia encouraged public opinion in the US, Europe and Islamic countries to believe that the UN could take effective steps to end the wars and protect the Bosnian Muslim population. In reality, the UN operation was fatally compromised by political disagreements among the leading Western powers, and between the West and Russia. In addition, national governments refused to give the UN the resources necessary to implement the Security Council's tough- sounding resolutions.
As a result, the UN took much of the blame for an indecisive policy that was really the fault of some of its most prominent member states. Decisive action in Bosnia required a partisan force in the shape of Nato, and it is a measure of the complexity of Balkan disputes that even Nato's intervention is not guaranteed to produce a stable regional peace.
In Rwanda, the failure to prevent one of this century's largest and cruellest slaughters has led the UN's critics to dismiss the organisation as sluggish and utterly ineffective in a crisis. As in former Yugoslavia, however, it was national governments, in Africa and abroad, that bore primary responsibility for failing to orchestrate an adequate response to the Rwandan genocide.
To improve its image, the UN badly needs the world to stop piling impossible duties and burdens of expectation upon it. The UN cannot end wars if the combatants want to fight on and if influential third parties lack the will for intervention. It is effective only insofar as national governments pursue clear policies and are not obstructing each other.
That said, the UN can do some things to put its house in order. It can clean out the stables of its rogue agencies, such as the World Health Organisation and Unesco. It can cut budgets more drastically than so far attempted and eliminate obsolete agencies and programmes. Indeed, the UN will have to take these three steps if it wants to restore its relationship with the US, which remains the chief financial contributor even though it owes more than pounds 800m in unpaid dues.
For all its sins, the UN remains the one organisation where governments and people from all around the globe can meet in the hope of lowering international tensions and reducing mutual suspicions. It offers mechanisms for overcoming conflicts which, if governments are in the right mood, can be made to work. In short, to paraphrase Winston Churchill on democracy, the UN may not be perfect, but nobody has yet invented anything better.