Security at army and police bases in south Armagh have been stepped up amid fears that dissident republican forces have been gathering strength locally, according to security sources in the North.
The sources say there are concerns that the "Real IRA" will chose this point to launch an attack on a military or police target in the North.
Fear of a night attack has led to all unnecessary lights being extinguished at the bases in the past week.
According to local republican sources, Provisional IRA leaders in the area are concerned that their hold in the area is slipping. The immediate aftermath of the Provisional IRA's historic decision to open its arms dumps for examination is expected to be a delicate time for the movement.
Garda sources report there has been relatively little defection to dissident republican groups since the main split in 1997. That was precipitated by the decision of the IRA army executive to allow for the decommissioning of weapons.
The dissidents walked out of that meeting in Donegal and set up the "Real IRA" group subsequently responsible for the Omagh bombing in August 1998.
However, in recent weeks there has been an unknown, though probably small, number of defections in the south Armagh area.
The dissidents are reported to have grown in strength and confidence in what was previously one of the IRA's principal heartlands.
According to sources in the south Armagh area, the local Provisional IRA figures are concerned that there could be further slippage to the dissidents. It is reported that a meeting of Provisional IRA members was called in the past fortnight and warnings issued by local leaders that defections to the "Real IRA" would lead to retaliation.
The dissident group has already attempted two mortar attacks on military bases, at Roslea in Fermanagh and in south Armagh.
It has also attempted to fire a Russian-manufactured rocket at a police barracks in Co Tyrone and has planted two bombs, both of which failed to explode, at army bases in Derry.
It also planted a bomb, which also failed to explode, at the Secretary of State's residence at Hillsborough, Co Down.
The group also managed to establish a unit in London, which was responsible for planting a small bomb under Hammersmith Bridge last month.
According to security sources in the North, it appears the "Real IRA" is improving its operational ability and it is only a matter of time before one of its devices explodes at or in a security installation in the North.
If it succeeds in finally carrying out such an operation successfully this might attract further support from disaffected Provisional IRA republican elements.
However, it is known that the Provisionals have put a great deal of effort into preparing membership for the events of the past few days.
Over the past two years the IRA has been reorganising its arms dumps, moving weapons where they might be vulnerable to theft by elements opposed to the Belfast Agreement.
The operation of storing the weapons in areas where the IRA believes it retains loyal support was under the direction of the "Southern Commander", a Belfast man who lives outside Dublin. It is reported to have gone smoothly. There are unconfirmed reports that weapons were moved to safe hides in Donegal, Monaghan and south-western counties where traditional support for the Provisional IRA and Sinn Fein remains in place.