The Taoiseach has applauded the election of Mr David Trimble and Mr Mark Durkan as the North's First and Deputy First Ministers and condemned "opportunists and wreckers" who want to bring down the Belfast Agreement.
The Taoiseach, who was speaking on Wednesday night at the Forum of Public Affairs of the Kennedy School of Government in Harvard, also made clear his strong support for the US campaign in Afghanistan.
Last night Mr Ahern travelled to New York where he had been due to meet the UN Secretary-General, Mr Kofi Annan. The meeting, however, had to be cancelled as the Government jet was grounded in Washington due to technical problems and Mr Ahern had to take a commercial flight. He is expected to visit Ground Zero this morning before returning to Washington today for an All Hallows reception at the Irish Embassy - he is also due to appear on CNN's Larry King Live.
"There are those, unfortunately, who want to stop the Good Friday agreement in its track," he said at the Forum. "They are determined to use every device and every opportunity to frustrate progress. They want to return Northern Ireland to the failed divisive politics of the past. "But the time has moved on. There is no going back. We have a chance to consolidate the peace - from which everybody has benefited hugely - and build a future that is fair and inclusive for all the people of Northern Ireland."
The decommissioning decision had broken a log-jam in the peace process that could now "progress as we thought it should". He paid tribute to those involved, including Sinn FΘin, but added it was important that all parts of the community got involved in new policing structures.
"I hope that, in time, Sinn FΘin and their community, who have shown such leadership in other areas, will also do so," he said.
The full functioning of the political institutions would require all parties "to reaffirm their commitment to playing a full and generous part, and to ensuring that others involved are able to do likewise."
Mr Ahern expressed his solidarity with the US over September 11th. "We stand with you and the rest of the international community in asserting that those who perpetrate them [terrorist acts] cannot be allowed to succeed. We must all work together to eliminate this scourge, and governments everywhere must dedicate their total commitment to this task."
He insisted that the UN must have "a pivotal role to play in achieving this" and spoke of the work done by Ireland in the Security Council to establish "permanent barriers across the entire international community which will comprehensively put an end to terrorism's capacity to operate."
Mr Ahern stressed the urgency of work on two fronts, to bring humanitarian relief, and to put a political settlement in place in which the UN would play a key role. After his address Mr Ahern took questions from the large, predominantly student audience. Asked if he thought the US should have sought specific sanction for its bombing of Afghanistan from the UN Security Council, Mr Ahern said: "No, they are quite entitled under Article 51 of the Charter to act. It was quite clearly in self-defence."
He said that the US did go to the Security Council on October 7th to outline its actions, but they were clearly within their UN mandate. In any case, he said, Resolution 1368, passed after the September 11th attacks, "well covers" not only action in Afghanistan but also - if they could demonstrate a case - wherever they could show that terrorism was operating.
Suggesting he personally would not favour extending the campaign beyond Afghanistan, the Taoiseach said, however, that the US had moved "very responsibly, slowly and carefully."
Asked if he would share power with Sinn FΘin, Mr Ahern repeated his insistence that to do so would be constitutionally improper while the IRA continued to exist. He said of the leadership of Sinn FΘin, specifically Mr Martin McGuinness and Mr Gerry Adams, that "their ultimate goal is to see the day when they can convince the IRA to wrap-up totally and disband completely, and that will change things."
On British non-membership of the euro zone, Mr Ahern said: "I do think Tony Blair will get around to holding a referendum. We're all in favour. I will even go and help him in the campaign."
