Experts on conflict resolution say the only way to settle a dispute such as the Northern Ireland troubles is to persuade both sides they have won. We do not have a "win-win" situation at the moment. Most observers are agreed the republican movement pulled a master-stroke by calling the ceasefire when it did.
It has badly wrong-footed the unionists, putting them in a position where, if they now reject the Anglo-Irish joint document on decommissioning and walk out of the talks, they will be seen as unreasonable in the eyes of the world.
After the slings and arrows of the Westminster election campaign, few expected the Hume-Adams partnership to be revived so quickly and to deliver a cessation of IRA violence in such short order. Their previous efforts had fallen on stony ground when the Major government either could not or would not co-operate. When New Labour came to power, Sinn Fein strategists were among the first to sense that there had been, not just a change in government, but an alteration in the whole political landscape.
They read the situation better than the unionists, who clearly did not expect the rebuff they got on decommissioning. It is not every day a London administration holds firm and refuses to budge in the face of unionist demands.
Nationalist sources in the peace process are also giving a great deal of credit to the Taoiseach, Mr Ahern, and his adviser, Dr Martin Mansergh, for creating the circumstances which led to the ceasefire.
"Bertie played an absolute blinder," sources said. "He got stuck in right away. He said to Blair, `give me a month'. He has been working on it night and day."
It is a dramatic time in Northern Ireland. After the Garvaghy Road debacle and the placing of nationalist residents under martial law for nine hours to facilitate an Orange march, sources said Gerry Adams could whistle for his ceasefire. But the turnaround came within a week when Adams showed that "people power" could face down the perceived threat from Orange marches and bring victory where guns would only bring chaos.
As always in the peace process there was considerable activity behind the scenes, with positive noises coming from the US in particular.
As with the last ceasefire, there are concerns on the part of unionists in particular as to how genuine and long-lasting it might be. Every incident, however minor, over the next six weeks and more will be parsed and analysed for its meaning and implications.
The mood in the unionist camp is sour, disillusioned and extremely wary; among nationalists there is hope and a determination to get results this time around. SDLP sources say the party is totally united behind the leadership: "It's the opportunity we've been waiting for."
The Ulster Unionist leader, David Trimble, faces a situation remarkably similar to the one he had to contend with last year over the chairmanship of the Stormont talks.
On that occasion he held firm and refused to be panicked when the Rev Ian Paisley and Mr Robert McCartney objected vociferously to Mr George Mitchell as chairman.
This time around, Trimble faces a much more serious challenge. Kalashnikovs and Semtex are a more obvious threat to the union than a mild-mannered former US Senator.
Unionist sources say the real threat to Trimble does not come from Dr Paisley and Mr McCartney but from within his own party, both at parliamentary and grassroots level.
"We don't have much room for manoeuvre," moderate unionists say. Today, Sinn Fein representatives will travel the Stormont Mile, negotiate their way around the Carson statue and present themselves at Castle Buildings. Unlike previous occasions they will be admitted, if only to "check out" office facilities. It will all be on TV and every unionist who can bear to look will see it. Their sense of betrayal will be heightened by seeing the political associates of republican paramilitaries receive the blessing of the establishment.
The nationalist hope is that the mood of realism in the unionist community which led to the compromise over Orange marches will come to the fore once again and permit Mr Trimble to stay on board.
Unionist sources are pessimistic. The situation is very dangerous, unless the Prime Minister can pull some rabbit or other out of the hat in London this afternoon and shore up Mr Trimble's position against his enemies, without and within.
Never say never in Northern Ireland politics these days, but unless there is a significant intervention by Mr Blair, even moderate unionists are resigned to voting against the Anglo-Irish decommissioning document on Wednesday, thereby undermining the talks process in its present form.
But politics is the art of the possible. Mr Blair's determination and vigour have brought about an IRA ceasefire, so it may not be beyond him to devise a face-saving formula to keep Trimble "on side". Unionist sources speculated about the possibility that they could vote against the document but without causing a complete collapse of the talks.
Whatever the unionists do now, the firm stance by the two governments has probably ensured that the decommissioning issue has already in effect been put to one side, or in Mr Trimble's own phrase, "pigeonholed". Many people, including even the odd unionist, believe that is what ought to have happened a long time ago.
The real issue, that of consent, is already beginning to come into focus once more. That will be the Sinn Fein leadership's great test: can they persuade their followers that the non-violent approach to partition will undermine it more effectively than the bomb and bullet ever did?
The various parties on both sides are staking out their positions in the short term and many politicians are thinking no further than Wednesday. But there is also a sense that this time, at long last, the pieces may be about to fit.
Instead of the smoke and noise from bombs and bullets there is a tantalising hint of a different aroma, familiar from other jurisdictions: the smell of power, high office and prestige. Northern Ireland's politicians have a long history of resisting such enticements but surely even they cannot hold out for ever.