In the past year, particularly in recent months, the republican leadership has been conditioning its heartland for movement on arms. Good sources still insist that Gerry Adams and Martin McGuinness accept the notion of IRA decommissioning. But they may not be able to deliver in the terms currently demanded by David Trimble.

Mr Adams and Mr McGuinness have been keeping developments very close to their chest in these rounds of negotiations in London. Only a tight and inner circle within Sinn Fein is being fully briefed, according to senior republicans.

Mr David Trimble, as he considers whether to "jump first" on the question of government versus guns, must weigh up conflicting advice and signals. He hears that the republican "seismic shift" is still on the Richter Scale of possibilities, but is also told that republicans are playing a dark game.

Senior British army and RUC security sources say there is and was no seismic shift in republican thinking. This message, one expects, will have been transmitted to Mr Trimble as he deliberates on whether or not to deal. But are the security figures right? Republicans in different parts of Northern Ireland, and at different levels of seniority, generally reject the security analysis.

One senior source said he was convinced that with Mr McGuinness and Ms Bairbre de Brun in an executive decommissioning would follow, but that it was "dangerous territory" to expect the IRA to make a prior commitment.

"If agreement could be found there would be a great sigh of relief within republicanism. I don't think it would be difficult to sell to the IRA. You must remember that interwoven into all this is the factor that republicans don't want to go back to war. There is a good chance of a deal, yet it might not happen."

Another republican, highly sceptical about the whole peace process, but equally resigned to the fact that republicans are locked into it, referred to a Financial Times interview in June 1998 in which Padraig Wilson, the IRA's commander in the Maze prison, predicted that if the institutions flowing from the agreement were in place then "voluntary" IRA decommissioning would happen.

"There is no way that he [Wilson] would make a comment like that without the approval of the leadership. It not only sent a message to unionism, but to grassroots republicanism," said the source.

"Each and every assurance over this entire process - no Stormont, no Mitchell principles - has been broken. I expect the assurance on guns will also be broken. And my judgment is that most republicans will not be a bit surprised if there is a deal involving decommissioning. They are being told it won't happen, but they are being conditioned that it will," he added.

"Even people who are disillusioned still have loyalty to Gerry and Martin. The most they would do would be to walk away, rather than walk somewhere else. I've been trying to analyse it and what I've come up with is that this process has become a way of life for many republicans. They might not agree with a particular decision, but they are willing to accept it," he said.

Mr Mickey McMullan, who served 18 years in prison on IRA charges, wrote recently in the London Observer that IRA decommissioning "subject to approval by Gen de Chastelain, should happen."

Curiously, speaking to The Irish Times, he also referred to the Padraig Wilson interview last year. "It's the old argument, constitutionalism versus militarism, but republicans need firm evidence that constitutionalism can work. They have no evidence of it up to now. They suspect that unionists are trying to drag this on until May," Mr McMullan said.

"If politics is working, and seen to be working, everything is possible. It's an entirely new ballgame," he added.

The talks could collapse in London this week, but if there is a sniff of a deal the parties will almost certainly return to Belfast for the denouement. Adams and McGuinness won't need any Civil War reminders about de Valera in Dublin and Collins in London.

Tony Blair's press secretary, Alastair Campbell, said during the Way Forward talks in July that if people knew just how close the two sides were to agreement they would be totally baffled by any subsequent failure. Yet the July talks did fail over whether or not there had been a shift in the republican position on weapons, and could do so again now.

Senator George Mitchell, as he goes about his business with the pro-agreement parties, knows that the gap between the Ulster Unionist Party and Sinn Fein, while tantalisingly narrow, is still out of reach.

At least, and at last, there is a sense of the talks temperature rising. There is a growing tension. Something is beginning to happen. Signals are being sent. Mr Adams, responding to unionist and loyalist demands for a little bit of abject sorrow for past republican wrongs, was conciliatory and reasonably contrite in his statement on Sunday. Some choreography here.

Mr Trimble isn't giving much away, but after an assured performance at his party's recent annual conference he is acting with the air of a determined and confident politician.

All of this is making the anti-agreement camp within the UUP rather edgy. In a less than subtle swipe at Mr Trimble, they told "Senator Mitchell, Tony Blair and Peter Mandelson" that they would not accept any fudge on weapons. But we know for whom the message was really intended. Guns before government, they said.

The response from the UUP Assembly team was interesting, ironic and almost dismissive. They welcomed "the support" from the dissident MPs, and reminded them that party policy was to "work towards the full implementation of the agreement."

But if the agreement is to work the trick remains how to close the gap between Sinn Fein and the UUP. Mr Adams hinted at possibilities opening up in his statement on Sunday, but as so often with Sinn Fein statements one had to comb through his words "theologically".

The key sentences from Mr Adams were that the UUP demand for IRA decommissioning "is also outside the terms of the agreement, but Sinn Fein would not be dogmatic on this point if there was some way of meeting the UUP demand. The reality is that the UUP position is not do-able . . ."

Pretty convoluted, and even contradictory, but Mr Adams appeared to be indicating that if Mr Trimble softened his position of requiring a prior IRA commitment to disarm - tantamount to surrender as far as republicans are concerned - then those in Sinn Fein and the IRA might budge on the guns question.

What is vital for republicans is that any compromise on arms can be sold to its base as a "voluntary" gesture. That was obvious from republican opinion canvassed for this article.

One thing is for sure. If this review is to succeed, greater precision of language will be required to satisfy Mr Trimble and his colleagues. As well as the focus on product, as in guns, much thought will be given to the choice of language in this final, nervous phase of the negotiations. Is it time for P. O'Neill to tell us something?