Analysis: Many people will be wary of talk of a "historic" breakthrough, writes Frank Millar, London Editor.
Gerry Adams is right about one thing at least: history will not judge kindly anyone who plays politics with a real choice between peace and conflict on the island of Ireland. Yet the Sinn Féin president might allow that the same holds true for him.
In throwing out his challenge to the unionist leadership, Adams can probably be confident that the Rev Ian Paisley's first response to yesterday's IRA statement will not be his last. A huge responsibility rests upon the Democratic Unionist Party.
Charged with the leadership of the unionist majority, the DUP's purpose is to seek a settled and stable Northern Ireland within the United Kingdom.
At every point in this unfolding process, therefore, Paisley and his colleagues have to question whether that purpose is advanced or achieved by the exercise of veto and the politics of exclusion. Yesterday's apparently "unilateral" republican initiative will have served notice upon them that they will have to constantly raise themselves above the level of a mere blame game.
However, Adams would be unwise to assume the outcome will be determined by the early British and Irish governments' rush to judgment in the republicans' favour.
Ian Paisley's leadership position is not the result of any accident of politics. It derives rather from the failure of a succession of previous republican initiatives to match words with actions.
So what of this initiative? Is this the IRA "surrender", foretold by yesterday's Sun newspaper? Or, if not surrender, does it represent - as Taoiseach Bertie Ahern appears to believe - victory for constitutional republicanism, the end of the Provisional IRA and the acceptance that violence has no possible part to play in the pursuit of a united Ireland?
Should Ulster's unionists, like democrats throughout the island, be dancing in the streets? Or is this an elaborate republican deception which might yet allow the political leadership of the republican movement to exercise power without responsibility, while leaving its army council to transform itself into some form of mafia commission?
That these and so many other questions suggest themselves on foot of yesterday's IRA statement should give Downing Street pause for serious thought.
The word from there on Wednesday night was that if anyone had to call in search of clarification, then the long-awaited statement by the leadership of Óglaigh na hÉireann would not have served its purpose.
Yet despite the prime minister's rhetorical flourish yesterday - describing the statement as "unparalleled in its magnitude" - even Blair was unable to say definitively that it would deliver the clarity, permanence and transparency required to see the power- sharing institutions restored.
The White House, meanwhile, noted that "victims" would be among the most sceptical and that words would now have to be followed by actions.
The scepticism, of course, is fuelled by the fact that it has taken so long to get the IRA leadership to this point. It is also compounded by the sight of Blair plainly feeling the hand of history once more upon him.
It seems little understood inside Number 10 that the events of recent years have severely eroded Blair's credibility as an interpreter of republican language and intent. Paisley was hardly alone yesterday in recalling the "seismic shift" in republican attitudes with which Blair, Ahern and then president Bill Clinton sought to bounce David Trimble's Ulster Unionists back into government with Sinn Féin after the first suspension of the Northern Ireland Executive.
Had Trimble not baulked at the last, the aborted deal of October 2003 would have been sold to the electorate as heralding the end of the IRA.
Likewise, last December, when the two prime ministers tried much the same trick on Paisley. They told a Belfast press conference that a historic DUP/ Sinn Féin deal breakthrough had failed on the sole issue of providing a photographic record of IRA weapons decommissioning.
It was only subsequently, courtesy of Tánaiste Mary Harney, that we discovered the IRA had also resisted demands by the Progressive Democrats for a statement recognising "the need to uphold and not to endanger anyone's personal rights and safety".
Gerry Adams and Martin McGuinness would doubtless complain this is more of the "whataboutery" which in their view has plagued the peace process for too long. Yet, as they well know, it is fed by what the British and Irish states have since had to say about the extent of IRA activity. Justice Minister Michael McDowell has branded the Provisionals an organised conspiracy, intent on continuing as a lightly armed gendarmerie.
Former Northern Ireland security minister Ian Pearson echoed the charge that the Provisionals ranked as possibly the most sophisticated criminal organisation in western Europe.
Who are people to believe - the Provisionals or two sovereign governments? Can the governments be surprised if public doubt is reinforced by Wednesday's extraordinarily cynical decision to release Shankill bomber Seán Kelly?
People will likewise be startled by suggestions in official quarters that "intelligence can kick in quite quickly", this seeming to prepare the ground for early pressure on the DUP to resume power-sharing.
If the Provisional movement is involved in half the activity the Irish Government in particular has suggested, how could two reports from the International Monitoring Commission within just six months satisfy the Irish or British public that all criminality has come to an end?
Or was it, as the Sinn Féin leadership has alleged, just Irish "electoralism" all along?
These rods for the governments' backs are partly of their own making. Will the IRA in "new mode" continue to recruit? What if Adams proves wrong in his belief that it is now possible to achieve Irish unity by purely peaceful means?
Some would have us believe this is just necessary deception of the republican base and that Adams understands the realpolitik of partition well enough.
Yet the Trimble leadership was partly undone by republican insistence that the Belfast Agreement was not a settlement but rather the transitional route to unity. Eleven years after the first IRA ceasefire, republicans have still to say they accept the legitimacy of the Northern Ireland state, its police force and its criminal justice system.
After the bellicose and threatening language of IRA statements earlier this year, Blair can claim to have banished the threat of resumed violence on his watch. Yet even now, we have no settlement but the promise rather of more process.
Right-thinking people will hope it eventually leads to accommodation and the new beginning promised in April 1998. But we should also allow that it might instead lead to a new point of divergence for politics in Northern Ireland.