ONLY the Provisional IRA has the type of explosives and the ability to carry out the attack which rocked the British army headquarters in Northern Ireland yesterday, senior security sources conceded last night.
It is believed commercial explosives, possibly Semtex, were used in the double car bomb attack which injured 31 people, including 10 civilians and two children, at Thiepval Barracks, in Lisburn, Co Antrim.
By late last night, no statement admitting responsibility had been made but the professional manner in which the attack was carried out has led senior security figures to blame the Provisional IRA.
Loyalist paramilitary sources indicated in advance of yesterday's attack that they were expecting a return to violence by the IRA and were preparing their own explosives to retaliate.
According to these sources, loyalists have been refining their explosive making skills and now believe they are capable of manufacturing home made explosive which is more powerful than that used by the Provisional IRA.
Loyalists have been predicting that the IRA would resume its campaign of violence in Northern Ireland, and that a response was "inevitable". They also warned that attacks in the Republic were likely.
The first bomb yesterday exploded only 100 yards or so from the main military administration blocks and homes of the commanding officers of the British army in Northern Ireland. The blast blew a crater eight feet wide and four feet deep in the car park.
The second device was placed close to the medical unit, apparently in an attempt to catch military personnel rushing to help those injured in the first explosion.
Sources pointed out that the IRA used almost identical tactics. in the Warrenpoint bombing in August 1979, in which 18 members of the Parachute Regiment were killed. The IRA have also used the secondary bombs with less effect on a number of other occasions since.
The bombs exploded as loyalist politicians from the Progressive Unionist Party were meeting Ulster Volunteer Force prisoners in the Maze, about three miles from the barracks.
It is understood the PUP delegation presented the prisoners with a document outlining their views on likely political and security developments in Northern Ireland. It is understood they put forward the view that the IRA was on the verge of restarting its campaign in Northern Ireland and that it would move on to targeting loyalists figures.
The Garda is now removing extra officers sent to the Border to guard against the smuggling of BSE infected cattle. Yesterday the last 300 gardai sent to the Border in May were sent back to their divisions.
Senior Garda sources pointed out that during the anti BSE exercise, it was estimated that 95 per cent of Border crossings were under guard at any given time.
The "static" checkpoints' mounted during the exercise are now being replaced by "mobile" patrols, which will cover an estimated 30 per cent of the crossings at any time. No additional military presence is anticipated on this side of the Border.
Loyalist sources in Belfast have insisted that attacks across the Border are likely in the event of a return of IRA violence to the North. Loyalists say they still believe the Government in Dublin is pursuing a nationalist agenda to undermine the North's position in the United Kingdom.