It was important to move the peace process forward because it would be "unconscionable and unacceptable to fall back or to accept a political stalemate", Taoiseach Bertie Ahern told the Dáil.
Opening a debate on the decommissioning of IRA weapons, Mr Ahern said there were those who remained unconvinced about the decommissioning. "I can understand that it will take some time for the full consequences of an ending of the IRA campaign and the decommissioning of all their weapons to be fully comprehended. But it is important also to begin to move on." It was not a time for "pessimism or undue delay".
He understood "the fears and uncertainties of the unionist community. I understand that trust needs to be rebuilt", but "it is also important that the new realities are recognised".
It was time to face other challenges, including the restoration of the political institutions, the ending of loyalist paramilitary and criminal activity and the resolution of policing issues.
Fine Gael leader Enda Kenny said the pressure was now on loyalist paramilitaries to respond in like fashion. He added that, while the completion of decommissioning was welcomed, the Provisional movement "has much to do before Sinn Féin can be fully regarded in the public consciousness as a truly democratic party".
It was hard to assume that because decommissioning was out of the way that those members of the IRA involved in criminal activities have suddenly ceased what became lucrative commercial activities for them, Mr Kenny said.
Labour leader Pat Rabbitte said that only when loyalist paramilitaries reciprocated "will we be able to say that all guns have been taken out of Irish politics". The onus now fell "on those leaders of unionism who have been so quick to question the validity of IRA decommissioning but so slow to move loyalist paramilitaries towards the same end".
"If parties such as the DUP are so eager to take the votes of working-class Protestants and to express the disenchantment and disillusionment of those communities, they must also act responsibly in ensuring that the peace be held in those areas that are most volatile."
Sinn Féin's leader in the Dáil Caoimhghín Ó Caoláin praised the "courageous and unprecedented step" by the IRA in formally ending their armed campaign and putting their arms beyond use.
He added that "for many members and supporters of Sinn Féin it appears that republicans yet again have had to leap first, but we in the leadership of Sinn Féin have said clearly that this development must be seen for what it is - an act of faith in the ability of Irish republicans to move forward together to our goal of Irish unity and independence by peaceful means".
Liz O'Donnell (PD, Dublin South) said that rather than eulogising the work of Sinn Féin and "those who have no conscience or tendency to apologies for these terrible acts, I think that this House should stand square and confirm our commitment to democratic politics and respectfully remember all those innocent men and women and also members of the armed forces who were destroyed and murdered by these weapons".
Closing the debate, Minister for Foreign Affairs Dermot Ahern said the "decommissioning of Provisional weaponry is a triumph for constitutional republicanism - a triumph for those of us whose main personal, and political, goal is the unity of Ireland and her people" and "who have seen the Provisional campaign bolster that partition and drive unity further and further into the future".