The decommissioning of paramilitary weapons is the issue that has bedevilled the peace process in Northern Ireland more than any other. It still does.

The crunch point on the issue has still not been reached - in a colleague's memorable phrase, it is a blockage that keeps being moved further down the pipe.

But that crunch comes nearer by the day.

Sinn Fein says it cannot deliver IRA decommissioning. It whiffs too much of surrender for a rank and file which has had enough difficulties with the Good Friday Agreement as it is.

Martin McGuinness: Sinn Fein's decommissioning negotiator

But the party has appointed Martin McGuinness, its leader most identified with the "physical force" side of the republican movement over the years, as its representative to the body responsible for decommissioning.

The Progressive Unionist Party, which represents the loyalist paramilitary group, the Ulster Volunteer Force, has appointed one of its most prominent leaders, Billy Hutchinson, as its representative. But he has warned that even if the IRA handed over its weapons, there is no guarantee that the UVF would.

When Billy Hutchinson's party had just one elected representative, it was put to him that they had no mandate. "Our mandate," he replied, " is the silence of the guns." To all the paramilitaries, that silence means the weapons are sufficiently decommissioned already.

Political dilemma

The political dilemma that all this causes is this: Sinn Fein has two seats, by right, in the executive (or cabinet) because of their electoral strength in the new devolved assembly set up under the agreement. Unionists object deeply to them taking those seats without any decommissioning having taken place.

But decommissioning, while it is due to be completed within two years of the signing of the agreement, is NOT a pre-condition to membership of the executive. Unionists say the handover of weaponry is a moral and political necessity - republicans say unionists are re-writing the agreement after the event.

And the executive is due to be in place by the end of this month, so cross-border bodies with the Irish Republic can be put in place.

In anyone's language, that is a stalemate.

David Trimble: Under pressure from his own party

The Ulster Unionists, Sinn Fein, and the nationalist SDLP have been meeting the prime minister to try to thrash out a solution, but everyone's room for manoeuvre is very limited.

David Trimble, the Ulster Unionist leader, and the new First Minister of Northern Ireland, is under severe pressure from some elements in his party not to touch a new executive containing Sinn Fein members - some unionists think republicans should never have seats there whatever the circumstances.

The party's annual conference this weekend should be a celebration party for Mr Trimble's winning the Nobel Peace Prize. But Ulster Unionists are not made like that - even Mr Trimble said he hoped the award was not premature.

Any peace process is, necessarily, as fragile as a house of cards. The fear is that decommissioning could bring it all tumbling down.