The third time was earlier this summer on the streets of west Belfast, where he was in charge of a dozen or more republicans. It was not far from the place where the two soldiers met their deaths. But this last occasion was a Sinn Fein operation, not an IRA one: he was in command of a scruffy little caravan outside a polling station in the Westminster election.

This republican's change of tack symbolises the route map being laid out by the IRA and Sinn Fein. The burly man, his colleagues and their leaders have not suddenly become pacifists: they have simply worked out that violence had probably delivered all it was ever going to.

The old dream was that, if they killed enough soldiers and others, then some British government would capitulate and surrender, leaving Ireland in the hands of the IRA, which would set up a 32-county socialist republic. This goal has been replaced by a new aim, which has the advantage of being conceivable in the foreseeable future.

Sinn Fein has already been crafted into a highly efficient political instrument, winning seats at Westminster and in the Dublin Dail. It has become the largest nationalist party in Northern Ireland, and has the capacity to grow further in both parts of Ireland. The aim is for the party to get into coalition on both sides of the border, thus wielding huge influence in both Dublin and Belfast, and pushing relentlessly for Irish unity.

Yet it has become ever clearer that an armed and active IRA was an obstacle to this scenario. Its potential coalition partner in the south, Bertie Ahern's Fianna Fail, made it clear that it would countenance no such deal while Sinn Fein has a private army.

The southern body politic has already undergone a remarkable sea-change in its attitude to the republican movement. Until this year it was prepared to give Sinn Fein a lot of leeway, on the grounds that the transformation from paramilitary to political takes time. But southern patience snapped following incidents such as the killing of Robert McCartney, the Belfast Northern Bank robbery, and revelations of republican criminality.

Sinn Fein and IRA denials of wrong-doing served only to compound the republican movement's credibility problem, and were contemptuously rejected. Republicans had to make amends, and yesterday's move was part of their efforts to do so.

For many months ahead, Sinn Fein will officially be in a type of quarantine. The IRA's language yesterday was strong and probably as ambiguous as Tony Blair and Bertie Ahern had hoped: now comes the period of scrutiny and verification.

If the IRA sticks to its word, with no surreptitious funny business, no more robberies and no more punishment attacks, then a few years down the road Sinn Fein could qualify as suitable coalition partners for Fianna Fail. The party would relish getting its hands on the levers of power.

North of the border, meanwhile, republicans have not only to re-establish credibility with the British Government but to convince a highly dubious Protestant community that they have changed. Specifically they have to impress one man - the Rev Ian Paisley, whose Democratic Unionist Party is, since the Westminster election, in complete control of Protestant politics.

It hardly needs saying that Sinn Fein is not Mr Paisley's first choice of coalition partner. But the DUP leader wants to be First Minister to crown his long career, and only a deal with republicans can deliver him that.

The irony is that republicans want the same thing, and recognise that they will have to work with Ian Paisley, their ancient enemy, to achieve it. A Paisley-Sinn Fein coalition would not be a pretty sight: it has already been predicted that it would produce "a battle a day".

But these would be political battles, not violent ones, with the burly Belfast republican using peaceful means and not the gun.