It could have been a disaster for the dissidents. Undercover British soldiers and police were lying in wait as republicans approached Garrison in Co Fermanagh last weekend to target a Catholic PSNI officer in his apart­ment.

The security forces, who had advance knowledge of the attack, could easily have wiped out the dissidents. Instead, they fired only two shots. Two men were later arrested and charged with attempting to murder the young recruit.

Republicans in Loughgall, Co Armagh, received very different treatment when they attacked the local police station in 1987. The SAS riddled them with bullets. Eight IRA men were killed.

But similar action last weekend wouldn't just have hurt dissidents. It would have been a far bigger disaster for the British government, the PSNI and Sinn Féin. "I doubt if Sinn Féin could survive a 2009 Loughgall. Republicans killed by the 'new, reformed police' would massively unsettle nationalist areas," says a south Armagh republican.

"When IRA men die in controversial circumstances, their neighbours usually stand in solidarity with the dead volunteer and his family, even if those neighbours don't support armed struggle." Leading Derry republican Gary Donnelly agrees: "The last thing the state needs now is martyrs. It doesn't want tricolour-draped coffins."

The bloodless arrests in Fermanagh weren't the only police successes last Saturday. Two men drove a 400lb car bomb through security barriers at the Policing Board's Belfast headquarters.

But the bomb – blamed on Óglaigh na hÉireann, a Real IRA splinter group – only partially detonated. Was that just bad luck for the dissidents or did the security services, through an informer, tamper with the device beforehand?

After Massereene and constable Stephen Carroll's murder, are the police and MI5 finally on top of the dissidents? Certainly, they're throwing huge resources at the battle. Dissidents, of both the military and political variety, are being targeted at a level surpassing that seen during the Provisional IRA campaign.

Gary Donnelly of the 32 County Sovereignty Movement says: "This year alone, five people have told me that MI5 have approached them to spy on me." The financial inducements for potential informers could appeal to some amidst a recession, particularly since the building trade – which employed thousands of nationalists – has been hard hit.

Hundreds of extra MI5 officers have been drafted into the North since Massereene. And electronic surveillance – in terms of bugging phones and homes and tracking cars – has advanced dramatically since 1994. The dissidents face a far more sophisticated and powerful Big Brother than the Provisionals ever did.

In an unprecedented move, 35 MI5 officers will give evidence from behind screens in Belfast Crown Court in April against three men accused of republican activity. The overwhelming majority of Northerners don't support dissident violence but the PSNI must walk a tightrope – preventing attacks but not alienating nationalists with heavy-handed tactics.

The number of people stopped and search­ed in the North under section 44 of the Terrorism Act has risen dramatically. In the three months to October, 10,265 people were detained compared to 1,657 for the same period last year.

Of the 10,265, only 39 were subsequently arrested. Civil liberties groups worry that PSNI actions look dangerously like harassment rather than genuine policing.

There's also a huge geographical imbalance – 2,203 people were stopped in Derry but only one in loyalist Larne. That might well reflect dissident strength in Derry, yet to some it can look more like old-fashioned sectarianism.

Brendan Shannon, a former Provisional IRA prisoner and member of the Republican Network for Unity, was stopped last week leaving his 11-year-old daughter to school in west Belfast: "It was ludicrous. How could someone be involved in an act of terrorism leaving a child to school? Other parents were horrified.

"I was also searched visiting my parents' grave. The police clambered over other graves to get me. If what's happening to republicans was happening to Muslims, there'd be outrage."

In Derry Magistrates Court last week, a policeman said he couldn't explain how republican Gary Donnelly had sustained a three-way spiral fracture to his left arm after being arrested.

Donnelly says: "I've been detained and searched dozens of times. When local people stop their cars or toot their horns, police take their registration numbers and they're harassed. This will backfire on the police."

Politically active republicans

Ex-IRA hunger striker and Old Bailey bomber Marian Price, now a member of the 32 County Sovereignty Movement, says the police have learned from some past mistakes: "They're generally not targeting the entire nationalist population any more, only politically active republicans.

"Some of our members stopped taking their cars to work because they were being constantly stopped. They started getting taxis but the police now follow the taxis and force them to pull over. Targeting well-known republicans sends a message to others thinking of becoming politically involved, 'If you do, we'll make your life hell'."

Price's west Belfast home was raided last week and she was arrested and questioned by detectives investigating Massereene. "My days of military activity are long over but it was a huge security operation. Eighteen police officers entered the house and well over a dozen others were outside with machine guns." Price (55) says she has no intention of ending her political involvement. During her 18-hour detention, she refused to speak to detectives, eat or drink.

South Armagh never became the dissident republican hotbed many suspected. However, one local republican says police still aren't served in shops in Crossmaglen: "Sinn Féin speak in favour of the PSNI but their supporters think they don't mean it."

While the PSNI doesn't stir up anything like the hatred the RUC did, the south Armagh republican says most people still wouldn't pass information to them: "The informer remains frowned upon. When the Real IRA mounted a checkpoint at Meigh recently, up to 50 local people saw it. My understanding is that no one phoned the police."

The PSNI has secured hundreds of Catholic recruits but most aren't from republican areas. "I know of only one south Armagh person who has joined – his family disowned him," says the source. "A policeman would be foolish to live here. The threat wouldn't just be from dissidents. Any local person with a few pints could take action."

A sign on the door of Republican Sinn Féin offices on the Falls Road in Belfast announces: "It is against the law to smoke in these premises." Inside, everybody smokes and other challenges to the law are visible.

Photos of Continuity IRA gunmen sit beside Che Guevara bodhráns. Christmas cards on sale show snowmen with rocket launchers and Santas with armalites. The talk is of the Provos 'selling out'. "Even the wall murals are insipid now," somebody complains. "Bart Simpson has replaced Bobby Sands."

Republican Sinn Féin vice-president Geraldine Taylor, one of the few women interned in 1971, claims there's growing disillusionment that the united Ireland Sinn Féin promised by 2016 isn't materialising.

She says pledges made when the party signed up to policing have also been broken: "They said the police would tackle ordinary crime here – well they don't. Old people are still being mugged, drug dealers are still dealing and people are angry."

Republican Sinn Féin's image is of old men with beards and geansaithe. So the election as party president a fortnight ago of Des Dalton (38) from Athy, Co Kildare, will surprise many.

Dalton, vice-president of his local Siptu branch, comes from a 'green' Fianna Fáil family. He joined Ógra Fianna Fáil at age 14, then graduated to the main party. However, at 17 he defected to Republican Sinn Féin, disillusioned after the Fianna Fáil government signed up to the Anglo-Irish Agreement and the extradition of republicans.

He acknowledges his party's lack of electoral support: "The challenge is to take stock, revitalise and refresh our organisation, to make republicanism relevant again and broaden our base. I've no doubt a job of work lies ahead.

"But I disagree when you say there is no support for republicanism in the 26 counties. Scratch the surface of almost every Irish man and woman and there's a republican underneath. Those instincts were illustrated by the opposition to the loyalist [Love Ulster] march in Dublin."

Republican Sinn Féin has recently formed two new cumainn in Dublin, plus cumainn in Kilkenny, Offaly and Westmeath. Last week, Gerard McManus (26) from Letterkenny, a member of the Irish Army Reserve Defence Force, was charged with the attempted murder of the PSNI officer in Garrison.

Southern militants

While militant republicanism will always be the pursuit of a minority in the south, its continuing existence surprises many. The election of Fergal Moore (37) from Monaghan as Republican Sinn Féin vice-president shows the party is serious about promoting young blood.

"Most people in the south aren't even aware we exist. We need to become more relevant to day-to-day politics, especially social and economic issues and workers' struggles. Contrary to the stereotype, the majority of our membership is under 40," he says.

But what attracts someone in the south such as Moore, who has a good job in engineering, to militant republicanism? "I oppose British rule in Ireland. Religious discrimination in the North has lessened, I won't deny that. But British rule has been updated and reformed, not ended.

"Catholics joining the police is irrelevant. The old RIC were 80% Catholics and they still dragged republicans from their beds." Moore refuses to condemn attacks on British soldiers or police: "As long as Britain occupies Ireland, there will always be Irish men and women resisting."

The peace process has made serious inroads into support for militant republicanism, but it would be a mistake to pretend that, on either side of the border, it has been consigned to history.