It is a troubled world whose leaders assemble this week in New York for the millennium summit of the United Nations, believed to be the largest gathering of its kind in history. The Taoiseach, Mr Ahern, was one of some 188 government leaders or heads of state to receive an invitation and he is due to address the assembly tomorrow.
Support for the UN is described as a "cornerstone" of Irish foreign policy. However, the UN is an unwieldy body where the necessity to achieve consensus often precludes the possibility of timely and decisive action. Its finances are in a critical state and there are major difficulties and question marks over its role as an international peacekeeper, especially since the end of the Cold War.
It often seems that member-states would prefer fine words to effective action and there will be no shortage of rhetorical pronouncements. The nightmare of those who would like to see the UN performing the role it was meant to carry out is that they will be left at the end of the week with nothing more than "motherhood and apple pie", with no improvements in the organisation's performance on the ground.
There is an urgent need to generate some political momentum but inevitably there are differences of philosophy between member-states over the correct approach. The fact that so many contemporary conflicts tend to occur within the borders of a state rather than between two warring countries has lent impetus to the idea of "humanitarian intervention". This has provoked a major debate, because it implies that the fundamental UN principle of respecting the sovereignty of member-states should be reconsidered. According to this view, tyrannical regimes should not be allowed to hide behind the sovereignty principle while they massacre groups of citizens.
There is considerable suspicion of the humanitarian intervention idea in some quarters, especially countries that have recently emerged from colonial rule and which see the doctrine as a cloak for a new imperialism. Their fear is that interventions based on greed for territory or resources could be disguised as humanitarian missions - an updated version of the "white man's burden".
Philosophical differences such as this tend to inhibit action in crises. The UN has not covered itself in glory over the past decade: where it has intervened, it has often been paralysed by its own rules of engagement, with a consequent growth of cynicism and disillusion in the wider world.
As a small country with limited resources, Ireland's influence has always been more moral than material. However, the success of the economy means that our material contribution can be more generous than it was in the past. The Taoiseach will no doubt highlight Ireland's aid programmes, particularly in Africa, and he is likely to mention the special focus currently being given to combating the AIDS epidemic as part of the Irish aid effort.
Mr Ahern is also expected to stress the Irish contribution to UN peacekeeping over four decades. He is unlikely, however, to explore the domestic political complexities surrounding this issue. Ireland is committed to the new EU rapid reaction force but many citizens would wish to see our traditional role in the UN maintained and perhaps even expanded.
At the same time, however, the people who hold the purse strings in Government are pushing for cutbacks in the Defence Forces. Something's got to give. If a sustained peace can be achieved in the North, it will obviously free Irish soldiers from Border duty. In theory, these troops could be transferred to duty with the UN or serve in Europe, although there are practical difficulties. Perhaps the European army rapid reaction force could have a place in the overall UN structure? The Taoiseach will probably not enter into these questions of detail today but his general observations on the role of Irish peacekeepers will be carefully parsed and analysed in military and diplomatic circles.
In addition to his brief speech to the assembly and a longer address on Ireland's place in the world to the Foreign Policy Association in New York on Friday, Mr Ahern will bring the current Irish campaign for a seat on the UN Security Council to a climax with a series of bilateral meetings with different member-states.
The votes of all countries carry the same weight so it is just as important for the Taoiseach to convince Albania as Georgia, and Micronesia's vote is worth the same as that of Nigeria. He will meet these member-states, along with others such as Slovakia, Hungary, Costa Rica and Ethiopia. At present, 11 formal meetings are arranged and he will no doubt apply his persuasive skills in an informal setting as well.
Ireland's rivals for two temporary seats in the West European and Other Group of States bloc on the council are Norway and Italy and the secret ballot is expected to be held in mid-October. The Taoiseach is also expected to have more broad-ranging meetings with Bill Clinton and Tony Blair.
The opening address tomorrow is to be given by the US President who will also take advantage of the presence of Israel's Prime Minister, Ehud Barak, and the Palestinian leader, Yasser Arafat, to boost the Middle East peace process. He is meeting each of them separately tomorrow and a trilateral encounter has not been ruled out. A summit-level meeting of the Security Council on Thursday will focus on peacekeeping issues, especially in Africa. A recent report by a UN panel under the former Algerian Foreign Minister, Lakhdar Brahimi, suggested numerous improvements in the organisation and conduct of peace operations.
The presence of Fidel Castro, who has requested a visa to head Cuba's delegation, will add a new dimension to the occasion. It would only be his fourth visit to the US since the Cuban revolution in 1959 and the subsequent ending of diplomatic ties between Washington and Havana. New York's Mayor, Rudolph Giuliani, has made it clear that as far as he is concerned Mr Castro is not welcome.
If allowed to attend, the Cuban president will not be the only politician to attract media attention on a guest list which also includes Vladimir Putin, Robert Mugabe, China's President Jiang Zemin, Czech President Vaclav Havel, and the Iraqi Deputy Prime Minister, Tariq Aziz. New York will be crawling with secret service and other security personnel and traffic will be plunged into chaos by the never-ending procession of official limousines.
UN Secretary-General Kofi Annan has already proposed an agenda of work for the member-states, with ambitious targets on world poverty, AIDS, education, the environment, the debt burden, disarmament and alleviating the negative aspects of globalisation. A nine-page assembly declaration will be endorsed, enshrining the principles of freedom, equality and tolerance.
Treaties and conventions are due to be signed on such issues as human rights, the banning of landmines and the establishment of an international criminal court. There will be no shortage of fine words from the political leaders: the question is what they will do when they get back home.