Within hours of the dissident group which claims to be the "true IRA" declaring that military attacks would resume, a huge security operation was visible on the streets of west Belfast.
Local people said that such a level of British army and RUC activity had not been seen since the IRA ceasefire. The security forces set up dozens of checkpoints.
In Dublin the Fine Gael leader, Mr John Bruton, told a party rally in the Peace Garden that all the parties to the Belfast Agreement had an obligation to "disable" the "new IRA."
An RUC spokesman would say only that "security matters are under constant review."
But privately security sources expressed concern. "This is the split we all knew would happen," one said. "The next few weeks will be vital. We don't know how it will go. So far the dissidents have been restricted to Border areas and the Irish Republic."
The new organisation is led by some senior IRA members, including the quartermaster-general who resigned last October in protest at the peace process. Security sources believe they have about 150 members and access to IRA arms dumps.
In their statement on Friday they called on all IRA members to switch allegiance from the "old leadership", which they claimed had betrayed republicanism, to the caretaker army executive they have set up.
A series of meetings of republican activists in Belfast last week showed deep divisions in the IRA. While many IRA members denounced the Belfast Agreement, equally passionate statements were made in favour of the leadership.
Sources on the pro-agreement side said leading republicans such as Mr Gerry Kelly, Mr Bik McFarland and Mr Martin Meehan have been instrumental in keeping sceptics on board.
The mainstream IRA is vigorously challenging the dissidents' claim to be the true IRA. Among Sinn Fein members in Belfast there is incredible bitterness towards the dissidents, who are regarded as disloyal and treacherous.
In grassroots IRA circles, however, they are respected for their "contribution" to the republican campaign over the years.
The dissidents share similar political views to those of the 32County Sovereignty Committee, which is due to hold a meeting in Belfast on Friday. But even the turnout at this event might not give a clear indication of support for the dissidents, as traditionally many IRA members do not attend public meetings.
Sources close to the dissidents said recent Garda successes resulting in their losing both personnel and weapons have meant they will be putting security factors before their desire for high-profile operations.
Many of the dissidents believe the mainstream IRA leadership has passed on information about them to the security forces. Some RUC sources believe a feud between the two groups is possible.
The dissidents, however, have stated they have no desire for such a fight. While some figures in the mainstream IRA believe the dissidents should be dealt with, their hands are tied by the peace process.
It seems unlikely that the Pro visionals would act against the dissidents in advance of the referendum or next month's assembly elections.