The spying game - how to beat the IRA

From Agent Stakeknife to high-tech bugs, the forces of the Crown have far greater intelligence resources than the terrorists. As David Trimble and Gerry Adams fight over the remains of the Good Friday Agreement, Andrew Gilligan reports on a very different conflict

Someone in the Northern Ireland security forces clearly has a touch of showbiz in his soul. The spectacle of the police in their Swat gear marching through the halls of Stormont – Sinn Fein's Bairbre de Brun in shrill pursuit – made superb telly. And wasn't it lucky that the cameras were there to watch? But like most stories, there's more to it than the pictures.

The real evidence of the IRA's alleged "spy ring" in government was not collected by the bobbies in baseball caps rooting through the Stormont desks. The new disclosures were not isolated events, merely the latest and flashiest episode in what is normally a much more secret struggle – the intelligence war between Britain and the IRA. Even during the Troubles, at least in the later stages, the intelligence war was described by some as the real conflict. And it is a war – unlike the shooting variety – that is still being fought.

To the Ulster Unionist leader David Trimble, the IRA operation at Stormont was "10 times worse than Watergate". But for all the hyperbole, and worries about just what has been leaked, the fact is that the terrorists' intelligence operations are increasingly, and massively, outgunned by those of the British Government. Given the resources of the state, it would be a scandal were it otherwise.

The IRA may have a note of some of Tony Blair's conversations over recent Good Friday talks. But former ministers openly admit that in the run-up to the agreement itself, they were bugging Sinn Fein leaders' cars – and, no doubt, much more than their cars.

The IRA leadership may have unspecified "personal details" about Lieutenant-General Sir Alistair Irwin, the Army chief in Northern Ireland. But General Irwin, it is safe to assume, has rather more personal details about them. He has several hundred full-time military intelligence officers and a number of shadowy units – including 14 Intelligence Company, or "the Det", whose members, often women, infiltrate communities and observe suspected terrorists. The Force Research Unit (now renamed as the Joint Services Group) runs agents inside the terrorist organisations. And there's a wealth of technical goodies.

Tiny transmitters, hidden inside IRA weapons, alert security forces when someone comes to collect them. A database called Caister, or Crucible, holds intelligence information on most of the population of Northern Ireland. Another computer, Vengeful, tracks vehicle movements around the province, with the aid of hidden cameras which read number-plates; further systems cover telephone calls. The IRA's technological capability, by comparison, comes from a mixture of skilled improvisation, and Dixons.

As for the Real IRA, the group still at war with the British, it has had astonishingly little technical success. With one ghastly exception (Omagh), almost all its bombs have failed to detonate properly. Can it really be that incompetent – or are there other factors?

The IRA may have had the services of a messenger in the Northern Ireland Office. But it appears likely that the British still do have an agent on, or close to, the IRA Army Council. His codename is "Stakeknife", and he is one of possibly dozens of British assets and informers inside the main terrorist groups. At the other end of the scale, one British operative was an estate agent. He used to let local IRA men hold meetings, or sleep with their girlfriends, in his empty properties – which were, of course, bugged.

The estate agent operation was an early 1970s success – but many others of that era were amateurish, dogged by sheer ignorance of the new foe. By the Eighties, after 20 years of accumulated knowledge and agent-building, the balance of power in the secret war had shifted firmly against the IRA.

The journalist Ed Moloney, one of the best and closest observers of the Provisionals, is convinced that intelligence played a strategic part in the decline of the IRA's armed struggle. His new book, A Secret History of the IRA, recounts how hardliners planned a Vietcong-style "Tet offensive" to convince the British public that the "war" was unwinnable.

This offensive depended on a massive shipment of arms from Libya – but the ship bringing them back, the Eksund, was stopped off the French coast. The authorities claimed it was a fluke, but Moloney says the ship was betrayed by an informer at a high level in the IRA. The Provos never came close to acquiring such weaponry again. The Tet offensive had to be abandoned, and it was the IRA, or at least its leadership, which ended up conceding that the war was unwinnable.

Around the same time, mysteriously, some of the hardest of hard-line IRA units started to disappear. Between 1987 and 1992, 17 members of the organisation's Tyrone active service units were killed by the SAS, including eight on one day, as they prepared to blow up a police station in Loughgall, Co Tyrone. Troops always seemed to know what was planned.

By the end, the Tyrone IRA was all but wiped out – and the level of operations in the county, previously one of the most violent, more than halved. We now know that these were the very early days of the peace process. Most of the men killed would have been fierce opponents of peace with Britain – had they lived.

Dissident republicans suspect to this day that Stakeknife, the highly-placed British agent in the IRA, betrayed the Tyrone men – and, later, several others dubious about the peace process – in order to further his own agenda of dialogue.

Some in the Irish government even fear that Stakeknife deliberately condoned or initiated IRA operations targeting civilians – such as the Remembrance Day bombing of Enniskillen – in order to discredit Provo militarists. Some republicans suggest well-known names for the identity of Stakeknife.

All this may be a conspiracy theory too far. But it does illustrate the only way in which republicanism can turn the tables on its far superior enemy – by using British intelligence for propaganda. Persistent allegations of collusion with loyalist terrorists have left Britain somewhat vulnerable to this tactic.

Last Friday's TV raid on Stormont – together with anonymous "security source" stories in right-wing newspapers alleging dubious IRA activity – shows, however, that propaganda, too, is a game that both sides can play.

Andrew Gilligan is defence and diplomatic correspondent of BBC Radio 4's 'Today' programme.