IT would appear that the "Southern Command" of the IRA, which organises the bomb attacks in Britain, is either heavily infiltrated or has lost its capacity to organise bombing operations.

Since the ceasefire ended with the bombing of Canary Wharf on February 9th, four IRA bomb attacks have been thwarted, with heavy losses to the IRA of equipment and key personnel.

The first major setback occurred when IRA bomber Eddie O'Brien blew himself up on a bus in central London. Papers he was carrying led anti terrorist officers to lists of targets and details of the IRA operation in London.

O'Brien's team was withdrawn from Britain and replaced by more experienced members after a series of bombs failed to explode. Each time the security forces make a bomb find their technical experts gather crucial details about the IRA bomb makers, including occasional forensic evidence which could be used in court.

Experts can also determine from the design of bombs who the likely IRA engineer was, the manufacturing equipment he was using, as well as assisting bomb squad officers in defusing future devices.

It is possible the bombs which O'Brien's associates failed to detonate may have provided the security forces with information about the likely source of the devices.

A second team of bombers was sent to London to replace O'Brien's highly inexperienced and reckless squad. However, despite having considerably more experience in such operations, this second team hopelessly compromised itself.

The second unit set up a bomb assembly line at a house in Peckham Rye, London, which was raided by police on July 15th. More than 30 timer power units, boxes which contain the time and detonating mechanisms, were found.

However, no explosives were seized there and police on both sides of the Irish Sea became involved in an intense search for information which would lead them to the IRA's explosive store in London. The 10 tonnes of explosive found yesterday is almost certainly the store the police were looking for.

ASIDE from the setbacks in Britain, the gardai also made major inroads into IRA operations with the discovery of a major IRA bomb factory and storage bunker beneath a farm house in Clonaslee, Co Laois.

A surprising amount of bomb and mortar making equipment was found there on June 22nd, and it is understood that the haul provided gardai with considerable forensic evidence, as well as new technical information about IRA engineering techniques.

An attempt by the IRA to open another front by launching attacks on British army camps was also compromised. After damage was caused to Quebec Barracks, at Osnabruck on June 29th, the German police quickly named and issued photographs of four Irish people they wanted to interview about the attack. The IRA action on the Continent stopped from that date.

Senior Garda sources say the security force seizures, which have been accompanied by almost 30 arrests, will have a major impact on IRA morale.

In the aftermath of such setbacks, it will be difficult for the IRA leadership to convince its volunteers that they have much chance of surviving a bombing campaign in Britain or elsewhere.

There are also bound to be very strong suspicions that all the seizures and arrests are a result of intelligence reaching the security forces from highly placed informants within the IRA.

HOWEVER, there are also reports that some of the IRA's more professional bombers retired during the ceasefire period and that their replacements simply do not possess the needed expertise.

Security analysts are now likely to be considering the options facing the IRA leadership. Senior Garda sources have remained adamant that the IRA was about to hold a General Army Convention and were confident that the pro ceasefire element, which supports the political path outlined by Mr Gerry Adams, were in a majority and liable to instigate a renewed ceasefire.

The principal fear was that before such a decision would be made, the IRA might want to launch one of its "spectacular" bomb attacks in Britain to prove it was retiring from a position of strength. This reasoning fits in well with yesterday's haul in London.

The other concern is that there may now be a level of instability in the IRA which could precipitate a crisis within the organisation at a critical time. There are clearly strains between those in the IRA who are for a ceasefire and those against. It is believed there is a majority within the IRA's Northern Command against restarting the terrorist campaign within Northern Ireland, which explains why that violence has not resumed there.

Such a renewed campaign would precipitate the loyalist paramilitaries, who have maintained their ceasefires, into retaliatory attacks. Renewed republican and loyalist attacks in Northern Ireland would, inevitably, include attacks on the homes of known republicans and loyalists and could also lead to widespread sectarian violence.

With the disintegration of the IRA's Southern Command bomb squads, militant elements in the IRA, particularly in the Border areas, might increase pressure for a renewal of attacks in Northern Ireland.