The Irish justice minister has said he believes senior Sinn Fein figures Gerry Adams, Martin McGuinness and Martin Ferris have left the IRA army council.
Mr McDowell said three senior SF members had left IRA army council
Michael McDowell said he did not think it "by itself amounts to a severance between the two organisations".
However, he said it was important as it acknowledged structured links between them.
The three Sinn Fein members have always denied being members of the IRA army council.
Meanwhile, Mr McGuinness is to brief US supporters about the IRA's intentions.
He is expected to travel to the US on Wednesday as part of increased activity in the past few days by the Sinn Fein leadership, which included meetings with the British and Irish governments.
The talks came amid expectations that the IRA may make a statement on its future later this week.
Mr McDowell said he looked forward to the statement, but added there was "no question of governments on either side of the border tolerating the continued existence of an unlawful organisation".
He said he the IRA needed to mutate into an organisation that was no longer involved in illegal activities.
Irish Justice Minister Michael McDowell
Decommissioning of weapons had to be completed "down to the last bullet", Mr McDowell added.
He was speaking at Castle Buildings in Belfast where he was formalising new arrangements which the British and Irish governments believe will help combat serious crimes such as drug trafficking.
Mr Adams and Mr McGuinness have previously denied any membership of the IRA army council as has Mr Ferris, a member of the Irish parliament.
The seven-man council runs the paramilitary organisation.
Mr McDowell said the move was "an acknowledgement, in my view, that there was a very structured link between them in the past".
Irish premier Bertie Ahern held talks in Dublin on Monday with a senior Sinn Fein delegation.
The meeting followed UK Prime Minister Tony Blair having a private meeting in Downing Street with Gerry Adams and Martin McGuinness.
Meanwhile, new UUP leader Sir Reg Empey has said the unionist community is "almost bored stiff" with statements from the IRA.
He was speaking on Monday after holding his first meeting with Mr Blair since taking over as leader of the UUP.
"The only thing that is going to matter is what the republican movement actually do," Sir Reg said.