The Taoiseach has said Sinn FΘin does not have the right to enter government in the Republic while the "structures" of the IRA are still in place.
On RT╔'s Morning Ireland yesterday, Mr Ahern was asked if Sinn FΘin could serve in government in the Republic as well as the North, following the IRA's recent move on decommissioning.
"My position on this has always been clear. I've stated that when the IRA had finally folded up its tent and when they had finally decided to end as an organisation, then that changed, that position, because constitutionally it can't be dealt with any other way," he said.
"They haven't crossed that Rubicon. I think they know that very well. I think that will happen."
Mr Ahern said the Sinn FΘin president, Mr Gerry Adams, and the party's chief negotiator, Mr Martin McGuinness, were on record as saying they would work towards the day when there was only one army in the State.
"We can't have two and we certainly still have the structures of another one," he said.
Mr Ahern said the IRA's move on decommissioning was probably the biggest breakthrough in the North since the Belfast Agreement was ratified. To have moved earlier, ahead of the broader republican movement, would have encouraged dissidents, he said.
He said he was convinced the leadership of both Sinn FΘin and the IRA had "their mind made up" on the issue for some months, but had wanted to bring the entire movement along with them.
He now hoped the political representatives of the loyalist paramilitaries could get into a position to carry their people with them.
Deadlines had "bedevilled" the peace process, but trying "to draw new lines around dates into the future" never helps.
