Taoiseach Bertie Ahern has said that rebuilding trust among participants in the Northern peace process would be neither quick nor easy.
Speaking at the annual Fianna Fáil 1916 commemoration at Arbour Hill cemetery, Mr Ahern said the Government was still awaiting a response from the IRA relating to a total end to violence and criminal activity.
He also described current armed republicanism as "a false ideology", and said that in order to avoid a "historic missed opportunity" the paramilitary organisations had to make "a radical response" in relation to the "rule of law" and human rights.
He said that, following the British election, the Government would be returning to the work of implementing the Good Friday agreement, which was its "main national priority".
"The Good Friday agreement represents an historic opportunity for all traditions on this island. It could and can only succeed with a sincere and complete abandonment of violence and law-breaking by all organisations previously involved in that."
This had to be demonstrated by "both word and deed outside of any short-term electoral context".
"I have asked the question (of the IRA). The question has been echoed. We have yet to receive an answer. The prospects of resuming fruitful dialogue depend on that answer.
"Rebuilding trust, which has been seriously damaged, will not be quick, and it will not be easy."
Mr Ahern's speech, made at the graveside of 14 of those who were executed or died during the 1916 rising, has become one of his keynote annual addresses on Northern Ireland, where he sets out the Government's agenda on the issue for the next 12 months.
Referring to his party's past, born out of the violence of the civil war, he said Fianna Fáil had been from the outset a republican party committed to a democratic political path.
He said a "healthy republicanism" was based on "equality of rights, opportunity and treatment, on the rule of law, and respect for human rights".
"A healthy republicanism never relied on the proceeds of crime or physical attacks and intimidation of those who dare to speak or behave differently. It does not assume the right to take the law into its own hands."
The Taoiseach said terrorism, "even when employed by a frustrated minority with real grievances" , had been a costly and "singularly unsuccessful method of liberation" in the modern world.
"If we are not to be faced with an historic missed opportunity, a radical response to the demand of people all over Ireland for strict adherence to democratic standards, the rule of law and human rights is required, not just from political parties but from associated paramilitary organisations," Mr Ahern said.
"We here, as the democratically-elected Government of the Irish people, have the right to lay down the high standards required of true republicans, rejecting false ideology that has held sway for far too long . . ."
He said there was "little prospect" of achieving the "more ambitious objectives" of the Good Friday agreement if "some cannot do what is needed of them".
"In 1998 the people did not vote for an armed peace. Or for a criminal peace. They voted for a democratic peace. We must have closure to build that democratic peace. Closure on decommissioning. An end to all illegal activities. No more threats and no more intimidation.
"If we can achieve that, then the unionist community must live up to its commitments to participate in government with all democratic parties.
"If the IRA is decisively removed from the equation, it benefits nobody for unionism to turn its back on partnership politics."