The recent "renewal of faith" by the United States in the United Nations has been described as a significant and welcome development by the Minister for Foreign Affairs.
Mr Cowen was addressing the National Committee for the Study of International Affairs which was holding a one-day conference at the Royal Irish Academy in Dublin under the heading, "The Crisis of 2001-Values and Interests in the International System".
He said the Bush administration had looked to the UN as a "central venue" for the follow-up to the terror attacks of September 11th.
"Even more important is that the UN has responded quickly and effectively," he added.
The US was also looking to the UN to play a central role in the post-military phase in Afghanistan.
The Bush administration had cleared a large proportion of arrears owed to the UN.
Turning to the impact of the September 11th events on the European Union, Mr Cowen said attention had recently been focused on the fact that a number of member-states, including Ireland, were not invited to the recent Downing Street dinner party of EU leaders.
He quipped: "I have eaten there on many occasions. The food is good, but Iveagh House is better."
The truth was that the EU had responded "with a very significant degree of cohesion and purpose" to September 11th and its aftermath.
Early next week he would be attending the EU's Capabilities Improvement Conference, which marked the next stage in the development of the Rapid Reaction Force.
The participation of up to 850 Irish troops had been authorised, which presented an opportunity to play a constructive role in promoting peace and stability.
On Afghanistan, he said it was crucial that the military campaign be accompanied by a "visible and effective" humanitarian strategy.
"There must also be a concerted international effort, co-ordinated by the UN, to assist the people of Afghanistan in establishing a broad-based government, representative of all the ethnic groups which make up the country," Mr Cowen said.
Prof Joan Hoff of Ohio and Montana State Universities said that until September 11th, the Bush administration had pursued "a singularly arrogant and unilateral foreign policy".
The US might be using the rhetoric of multilateralism at the moment and engaging in a temporary co-operative effort, but it would revert to its traditional unilateralism once the current crisis had subsided.
Explaining her theory of "independent internationalism", she said the US acted in a unilateral manner except in times of crisis.
US bombs had killed innocent civilians in Afghanistan, when Americans should have learnt from September 11th that bombing civilians was wrong.
"When you are the biggest hammer in the world, there is a tendency to see every problem as a nail," Prof Hoff said.