Analysis: An institution struggling under weight of history and hypocrisy built on good intentions, compromise and hypocrisy

The Iraq crisis could signal catastrophe for the UN. But it could also turn out to be one of the much-maligned organisation's finest hours

Some call it the ambassador's roll. It's the cocksure walk obscure diplomats develop as soon as their country is catapulted into the cockpit of world affairs, as the United Nations Security Council is sometimes grandly known.

Now in deadlock over Iraq, the future of the Security Council is suddenly in the balance, as America and Britain impatiently wait for the authority to wage war against Saddam Hussein. As the world's only institution solely dedicated to maintaining international peace and security, the weight of history hangs over these diplomats in a way few of them would have predicted when they eagerly lobbied to become members.

Depending on how its members vote in the next few days – if indeed a vote is called – the Security Council may be doomed to more years of irrelevancy at a time of unprecedented peril for the world.

How the tables have turned since Charles de Gaulle imperiously dismissed the Council as a mere machin (or thingy) which must never be allowed to stand in the way of his country's national interest. Now it is the Bush administration which is bridling at the restrictions of collective decision-making. A US ambassador once summed up these unilateralist feelings when he said he looked forward to the day that the UN untied itself from Manhattan and floated down the East River. There are well-founded fears that America may turn its back on the organisation and cast it back into the deep freeze of the Cold War years. The US, which pays a disproportionate amount of the UN budget, may even once again withhold its dues, as it did in the Reagan era.

These fears are dismissed by John Ruggie, a former adviser to the UN secretary general, Kofi Annan. "No matter how the vote comes out, in two to three weeks, the same countries will be back in the Security Council trying to figure out how to make the post-war situation work," he said yesterday.

There have certainly been plenty of bad moments since the UN was created in the aftermath of the Second World War by the five wartime victors – the US, UK, Russia, France and China – and 46 other states. The UN charter conferred veto power on the "big five" on the Security Council – the UN's executive arm – by stating that for resolutions to pass they require at least nine votes and "the concurring votes of the permanent members".

But hopes that the organisation would play an imaginative role in maintaining global peace were dashed by the rivalry of the Cold War years, as Russia and the US used their vetoes to neutralise the foreign policy objectives of the other.

The Security Council authorised military action in 1950 – in the absence of the Soviet delegation – to help South Korea repel the invasion from the Communist North. After that, the Soviets were back at the table, veto at the ready: between 1946 and 1955 the Soviet delegation vetoed a total of 80 resolutions, and a further 26 over the following decade. The veteran Soviet foreign minister Andrei Gromyko became known as Mr Nyet.

The Americans followed suit in the years after, most frequently casting their veto in support of Israel.

There was a brief period of euphoria as the Berlin Wall came down. Suddenly the permanent five members were discussing ways of stopping wars, rather than plotting against each other.

One of the results was a resolution which paved the way to ending the bloody nine-year Iran-Iraq war. Later, the permanent five cleared the way for Operation Desert Storm, which kicked Saddam Hussein's forces out of Kuwait.

But trouble returned again when the Security Council began to get involved in internal conflicts and in failed states. The former UN official Sir Brian Urquhart, known as the father of UN peacekeeping, points out that the UN Protection Force in Bosnia failed because it was a "fig leaf" of a peace-keeping operation with a flawed mandate. The massacre of Muslims by the Bosnian Serb army in the UN-protected "safe haven" of Srebrenica was a blot on the UN record.

The UN intervention in Somalia was similarly disastrous, when 18 Rangers died in an ambush while hunting the warlord Mohamed Aidid. Washington refused to commit troops for peacekeeping operations for years afterwards.

The genocide in Rwanda followed in 1994, with the UN Security Council taking the blame for failing to intervene.

Mr Annan, who was in charge of UN peacekeeping at the time of both the Srebrenica massacre and the Rwanda conflict, has learnt his lesson. Since becoming secretary general, he has recommended that the Security Council sends peacekeeping troops only into situations where they have an appropriate mandate, in appropriate numbers and where there is a peace to keep.

And despite having its obituary written in 1999, when Nato countries attacked the former Yugoslavia without a UN mandate, it was to the United Nations that the Americans turned when it came to reconstruction and the rule of law. The same is likely to happen with Iraq.

US relations with the UN have been strained since the Republican party began to dominate Congress. The rejectionist front, led by Senator Jesse Helms until his retirement, turned the UN into a whipping boy and deprived the world organisation of financial resources.

But Mr Ruggie turns the argument about UN relevance on its head. "Over the last two or three weeks, the UN has grappled mightily with its task, in contrast with what the US Congress has done to move the agenda along. Look at what the House Committee overseeing the congressional cafeteria has done: they've changed the name of French fries to 'freedom fries'. Put these two things together, and then ask who's irrelevant."

In fact the UN Security Council is no better and no worse than the governments who are its members. It is "simply an institution that reflects the policies of the governments who belong to it," says Sir Brian.

When the current crisis is over, says Mr Ruggie, there will be "short-term recriminations".

"On the US side, those who don't like the UN will say we told you so, warned you about this, let's think twice about coming back to this place. But the lesson has begun to sink in that military force by itself is not as useful as these people thought it was. It is very useful for breaking things and killing people, but not for building things on the ground. You need support and legitimacy."

That is a lesson which neither Britain nor the US appears to accept as their forces gird for war, with or without a second UN resolution. These are indeed perilous times for Saddam Hussein, but also for the Security Council once America chooses to ignore its decisions.

Highs and lows - key moments in the UN's history

1946: First meeting of UN Security Council held in London

1950: Security Council votes to defend South Korea from the North, in absence of Soviet Union

1956: Security Council sets up first peace-keeping force, to deal with the Suez crisis

1960: Soviet premier Nikita Khrushchev bangs his shoe on the Security Council table and tells the United States: "We will bury you."

1961: Death of Dag Hammarskjold, the UN secretary general, during Congo ceasefire negotiations

1964: Security Council sends peace-keepers to Cyprus

1967: Security Council adopts resolution 242 to provide peace for the Middle East after Six Day War

1972: Appointment of Kurt Waldheim, a former Nazi, as UN secretary general

1990: UN Security Council votes for Gulf War to liberate Kuwait

1992: UN Protection Force for Bosnia (Unprofor) to keep the peace in the Bosnian civil war

1992: Security Council imposes sanctions on Libya after Lockerbie bomb

1999: Nato bombs former Yugoslavia without explicit authorisation from the Security Council

1999: Security Council authorises East Timor peace-keeping force

2002: Security Council adopts resolution 1441 ordering Iraq to comply fully with weapons inspectors or risk "serious consequences"