Senior Ulster Unionist negotiators last night insisted there would be no climbdown on decommissioning, as the party's renewed civil war on the "no guns, no government" policy cast its shadow over the Mitchell review.
And there were signs of a hardening of Sinn Fein's position, with the party apparently determined that the review should end this Friday with a UUP decision to proceed to form an executive.
The renewed attack on Mr David Trimble's position from six Ulster Unionist MPs, and the former leader, Lord Molyneaux, came as the other pro-agreement parties prepared to rejoin the UUP and Sinn Fein in the ongoing review.
Today the new Northern Ireland Secretary, Mr Peter Mandelson, arrives in Dublin for talks with the Minister for Foreign Affairs, Mr Andrews, and Ms Liz O'Donnell at Iveagh House. In a joint statement the seven leading unionist dissidents - Mr Jeffrey Donaldson, Mr William Ross, the Rev Martin Smyth, Mr William Thompson, Mr Clifford Forsythe, Mr Roy Beggs and Lord Molyneaux - predicted UUP negotiators would come under "enormous pressure" this week to compromise on the arms issue.
And they warned: "We will not countenance the representatives of fully armed and violent terrorist organisations being placed in our government under any circumstances without an end to their violence, the decommissioning of their illegal weaponry, and the progressive dismantling of their paramilitary structures."
Mr Trimble's talks team issued a sharp response: "We welcome their support in the ongoing review and for our efforts to bring about a start to decommissioning. We are determined to secure the objectives of the Ulster Unionist Party.
"But we would remind our colleagues that party policy also commits all of us to work towards the full implementation of the [Belfast] Agreement. We trust we have their support for party policy on all of the issues confronting us in the review."
This was being interpreted as a positive indication of the UUP delegation's mood in some circles.
However, a senior party source said the statement should be seen in context, as a necessary response to criticism from party colleagues, and should not be interpreted as signalling any likely shift on the substantive policy issue.
Asked if Mr Trimble's requirement for a republican "commitment" to decommissioning meant acknowledgment by them of an "obligation" to decommission, and an indicative timetable, the source replied: "Absolutely".
While the review process is concentrating heavily on language which might help break the political impasse, Irish and SDLP sources say there is no indication as yet that Sinn Fein is willing or able to deliver a statement giving Mr Trimble certainty of achievement or an indicative timetable for decommissioning.
Some participants, however, have expressed cautious hope that a deal could be built around a redefinition of decommissioning. Until now the assumption has been that decommissioning would mean either paramilitary surrender of weapons to the International Commission, or voluntary destruction of them under the commission's supervision.
Another way - discussed and seemingly rejected last summer, but still seemingly favoured by some British sources - would enable paramilitaries to put weapons beyond use and to have them subject to periodic inspection and verification by an outside agency.