THE primary question, in the cold light of dawn, is not who is to blame for pushing matters over the brink, but how far we have to fall.
Reason argues that if the London bombing, and the statement calling off the ceasefire, are authentically the work and the responsibility of the IRA as a cohesive and undivided organisation, they represent a calculated and controlled gambit.
In that case, the actions were a clinically amoral tactical bid to shatter the political ennui and complacency constricting the peace process, to raise the stakes to the limit, and to seize the attention of the British public in the most shocking manner possible.
It is an extreme gamble. It risks sacrificing most of the political advances, international credibility and status painstakingly won by Sinn Fein in the last 18 months. It also opens a Pandora's Box of possible repercussions that could build into chaos.
However, because there is so much at stake, it must be postulated that the London attack may be intended to be a one off ploy. That is to say, there may be no intention at this stage - of a phased return to an intensive armed campaign. But there clearly is a blunt message that the IRA is willing to take that further step.
The best assessment of last night's events must be that they represent a single crude and imperative demand for negotiations. The effectiveness of that demand requires that the possibility of repetition is left very much open. It invites Mr John Major to take, in the IRA's terms, affirmative and positive political action - or to call their bluff.
To send this signal credibly however, the IRA had to formally announce the ending of the ceasefire as a whole - a hugely destructive step in political terms. It has thrown the Sinn Fein leadership into the most grave difficulties and disarray. A political domino effect has been triggered whose ramifications can barely be guessed at.
Last night's events force into stark prominence once again the intractable question of the relationship between Sinn Fein and the IRA - and they will not be allowed to forget that.
It is not a relationship that either organisation has been comfortable to have deeply probed in the past. The question now arises whether the IRA has dumped its political wing into the mire and reasserted the primacy of armed struggle over political work, or believes that the political wing of republicanism merely needed a small boost from the real power centre of republicanism.
It has been evident for some considerable time that militant elements in the republican movement were impatient, to say the least, with the pace of political progress.
They will argue that the last straw was John Major's flagrant leap frogging of the Mitchell report and the unvarnished adoption of the unionist agenda of elections in the North - a development which has encouraged unionist politicians to leap, with some relief, back into the old bunkers.
But nobody - neither British nor RUC intelligence, neither grassroots republicans nor nationalist politicians - apparently had any inkling that such a vicious and far reaching IRA riposte was on the cards.
Sinn Fein leaders, and SDLP politicians, have asserted that in deciding on the ceasefire of August, 31st, 1994, the IRA believed it was giving up violence in exchange for a part in the political process. That ceasefire statement, indeed, asserted that "an opportunity to create a just and lasting settlement has been created".
Last night's "IRA statement" accused Mr Major and the unionist leaders of "squandering this unprecedented opportunity to resolve the conflict".
Is there a glimmer of hope, however, in the final sentence last night which spoke of the failure "thus far" of the Irish peace process?
It is far too early to assess fully the damage that has been caused to the evolving political process - and to the vital psychological climate in the North.
Although Belfast and other points North were back on edge last night, the widespread response to the news was grimness and regret, rather than panic.
People had greeted the ceasefire of 1994 with restrained hope, rather than jubilation. The political developments since then had not augmented their hopes, although as the cessation continued they had begun, cautiously, to dare to hope a little more.
Equally, in these dramatic new circumstances, the community at large will let the politicians bluster and proclaim and rush to judgment. As the Alliance leader, Dr John Alderdice, put it last night "We are a resilient people . . . We've got to keep cool . . ."