THE Ulster Unionists are pressing the British Prime Minister, John Major, to define what he would consider "the characteristics of an unequivocal ceasefire" by the IRA. Party sources maintain that without "an effective lock" on any renewed IRA cessation, the Stormont talks are unlikely to move forward - despite Monday night's "breakthrough" on the agenda for the remainder of the opening session.
Mr David Trimble, the UUP leader, is expected to meet Mr Major in the next few days to discuss the issue which, sources say, has assumed greater urgency following Monday's agreement between the UUP and the SDLP.
The crucial element in that formulation requires agreement on "mechanisms" for dealing with decommissioning before the adoption of a comprehensive agenda, and the launch of the substantive Three Strand negotiations.
Senior SDLP sources last night confirmed that the issue of decommissioning illegally-held weapons remained unresolved. And they warned that if the UUP position remained as publicly declared, there would not be "sufficient consensus" to permit the talks to advance.
Rejecting suggestions that they had given way on the decommissioning issue, senior UUP sources last night revealed they want Mr Major "to list the criteria which would establish what a credible, dependable ceasefire would be...because there has to be agreement on what is to be done".
The unionists suggest Mr Major could act either by way of a definitive statement on the issue or by incorporating these "criteria" in the legislation to cover a decommissioning process due to be published next week.
The unionist strategy is to move the British government beyond its current requirement for the reinstatement of the 1994 ceasefire as the prerequisite for Sinn Fein's participation in talks. One source last night told The Irish Times "If we haven't received a redefinition of ceasefire in such a way that keeps Sinn Fein out, then our position (on decommissioning) is as was."
Mr Trimble yesterday gave the clearest signals that his purpose is to secure a commitment from London and Dublin to proceed with the talks process without Sinn Fein - in effect to re-establish the 1992 Brooke/Mayhew formula as the engine for seeking a political accommodation.
The Ulster Unionist calculation appears to be that the IRA bomb attack on the British army headquarters in Lisburn last week could force a significant shift in the attitude of the Government and the SDLP. But while the SDLP is clearly prepared to move into substantive negotiations, senior figures say they will resist any attempt by the UUP to reintroduce the old "Washington 3" pre-condition by the backdoor.
Mr Seamus Mallon, the SDLP deputy leader, yesterday welcomed Monday night's agreement on the agenda for the ongoing opening session of the Stormont talks. He said it could have "a symbolic and psychological impact on, the process and the participants".