The IRA crossed the Rubicon yesterday in saying that it will verifiably put its arms beyond use. This is indisputably a first, which will transform the terms of the peace process.
Six previous attempts to crack the arms issue have failed dismally, causing the Northern Ireland peace process to trail two years behind schedule. The present initiative is perhaps the most promising of them all.
Despite various allegations that republicans have over the years reneged on assurances they have given on decommissioning, no one has ever been able to point to any promise that they made.
There have been various Delphic and obscure comments, into which some have read a great deal, but they said nothing which has not been shrouded in ambiguity.
When David Trimble told Sinn Fein, for example, that he needed movement on arms to stay in office, republicans told him several times that they understood his position. Some assumed, wrongly, that this was tantamount to indicating that they would meet his needs; but this was never said.
This time it is different, for the IRA has finally used words such as "verifiable" and "beyond use". It is this which caused observers and politicians to speak yesterday of a dramatic and historic day for Northern Ireland.
As Peter Mandelson noted, the peace process has in the past made much use of creative ambiguity to get this far. It would be too dismissive to characterise this as the deployment of smoke and mirrors, but certainly many parts of the journey have been undertaken more in hope than in expectation.
Yesterday's IRA statement did not dispel all the clouds, but it did get rid of a great many. It was time for this to happen, because the conspicuous and continuing lack of trust between Unionists and republicans meant the time for clarity and certainty had arrived.
Previous attempts to break this deadlock were presented with much hype: everyone remembers the "seismic shift", announced during one bout of talks, which turned out to be no more than a distant tremor.
This new development was revealed to the world not with hype but with almost undue modesty. Expectations were deliberately dampened down by the two governments and almost everyone else, with only the wispiest rumours of a breakthrough escaping from Hillsborough Castle on Friday.
Tony Blair and Bertie Ahern played their parts in this, projecting the impression that no immediate breakthrough was in sight. One of those who spoke to them said: "I found them both very downbeat. They gave the impression, in fact, that Monday's talks with the parties in Downing Street had been seven hours of hell for them. They were actually pretty despondent."
It is now clear that they had a confidential blueprint which had emerged not from this week's few days of talks but from many weeks of Anglo-Irish talks and contacts with the key players. Furthermore, against all the odds, the plan had won the approval of Gerry Adams and David Trimble.
Most observers, unaware of the blueprint, had concluded that the two governments were moving farther apart. The leak of a document in which a British official described Irish foreign minister Brian Cowen of having "all the subtlety and open-mindedness that one would expect from a member of Sinn Fein" seemed to confirm that all was not well between London and Dublin. As always, there is no guarantee that this latest initiative will succeed. The IRA statement represents a huge advance but there are vital details still to clear up.
There is a certain logic to its move, however, in the sense that its previous flat refusal to think of putting arms beyond use had put it at odds with the nationalist population at large. The median nationalist, and even the median republican, has never seemed implacably opposed to taking guns out of the equation.
They have certainly been opposed to any type of decommissioning which would carry with it overtones of humiliation and surrender by republicans. But when it comes to a choice between saving the Good Friday Agreement and holding on to the guns for ever, most in the republican grass roots have quietly favoured the former.
The Protestant community may be deeply split in its attitude to the agreement, but almost all nationalists regard it as probably the greatest political document in Northern Ireland's history. This development puts the IRA back in line with the community's thinking.
There is always, however, a risk that the more hardline members of the IRA will take exception to all this. They have been assured that there will be no decommissioning, and it is not known whether some of them will see this new move as a betrayal of this promise.
Previous moves in the peace process have led to defectors setting up groups such as the so-called Real IRA. These are tiny splinter groups, but the 29 people they killed in the 1998 bombing of Omagh serve as a reminder of the destruction that can be caused.
Within Unionism, the problem lies not with tiny groups of armed extremists, though these do exist, but with the substantial section of the Protestant population which dislikes the agreement and indeed the peace process as a whole.
Around half of Protestants voted against the agreement two years ago, and since then more have become disillusioned with it. Those who have insisted on arms decommissioning can be divided into two camps. The first are those who oppose the peace process, and never want to see republicans in government.
The second camp is prepared to contemplate coalition with Sinn Fein but is yet to be convinced that the IRA's war is over, and wants to see decommissioning as proof of that. There will now be much debate on whether the new proposals offer certainty that the guns will stay silent.
No new deal can be put into place without the approval of David Trimble's Ulster Unionist party, and securing that will be tricky. Mr Trimble yesterday went first to his Assembly members, the party organ best disposed towards cutting a deal. But he may also have to face his party executive, which may be more sceptical, and he will certainly have to sell it to his party ruling council, which recently laid down that no government be formed without decommissioning taking place at the same time. Mr Trimble has committed himself to seeking the council's approval before going into government with Sinn Fein, so the scene is set for a key meeting.
He will be automatically opposed by the anti-Agreement elements in the party, who include most of the MPs, and to be successful he will have to convince the waverers of the scheme's merits. The result of this meeting will be unpredictable, in that strong contrary pressures will be at work on the 800-plus delegates.
They are not being offered decommissioning, at any rate as they have always understood it. But this is the seventh try at breaking the impasse, and some think it may be the last chance of doing so. It will clearly be a vital vote.
David McKittrick holds the Orwell Prize for Journalism.Reuse content