David McKittrick: There is only one way forward. But will it happen?

Immediate fate of the peace process and the Good Friday Agreement appears to be mainly in the hands of the IRA

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Past master of brinkmanship waits for republicans to deliver on arms

The immediate fate of the peace process and the Good Friday Agreement is mainly in the hands of the IRA. With his resignation, David Trimble has this time not just painted himself into a corner but cemented himself into it.

Realistically, there is only one way that the Assembly and other institutions set up under the Agreement will continue to function beyond the middle of August; that is if there is movement on arms, on a scale sufficient to impress not just Mr Trimble but also many of the doubters in his party. No one knows if this will happen.

Even the RUC's Chief Constable, Sir Ronnie Flanagan, with assessments from all the intelligence agencies at his disposal, frankly admits he does not know whether the IRA is going to make a significant move. The IRA has perfected the art of keeping secrets, and it has not lost the knack during the peace process.

The decommissioning issue has been dragging on for seven years, ever since the IRA cessation of 1994, and the organisation's ultimate intentions still remain unclear. Mr Trimble, in tendering his reputation, has no guarantee that his course of action will deliver. Tony Blair and Bertie Ahern have no guarantee that movement will come. They – and others involved – are proceeding on the basis of hope, and of an analysis that the IRA and Sinn Fein may have concluded that the time has come to deliver.

Yet everyone is aware that, within the closed world of the republican leadership, there are strong arguments both for and against making concessions on guns. The final decision may rest on the elusive answer to a fundamental question: whether the IRA and Sinn Fein want stability over the next few years, or whether they believe a period of instability would better serve their purposes.

While Unionists and others may complain that there has been no movement whatever on decommissioning, republicans point to their action in allowing international observers to inspect some of their arms dumps. They point too to the IRA's promise last year that it would, subject to a host of qualifications, put arms verifiably beyond use. Some Unionists dismiss all this as meaningless, others claim it is a firm promise that has been reneged upon.

Although in republican terms the inspections and the qualified promise represented a momentous step, the political value of these moves is now spent. This means that there is universal pressure on the IRA, internationally and from the massed ranks of leader-writers, to go further.

The IRA and Sinn Fein pride themselves on their ability not to buckle under pressure; Martin McGuinness's unflinching eyes are not those of a man who panics easily. Furthermore, while the outside world may be clamouring for republican movement, the nationalist grass roots have just elected four Sinn Fein MPs with the party's highest ever vote.

In the Republic, both opinion poll and anecdotal evidence suggests that Sinn Fein is well-placed to make substantial gains in the next general election there. This all strongly suggests that the voting public have few criticisms of make of how the republicans have so far handled the weapons issue.

It is also a fact that Mr Trimble has few enough fans within grassroots nationalism, so that in tribal terms his departure as Ulster Unionist Party leader would go largely unmourned in Crossmaglen and the Bogside. The leaders of the IRA and Sinn Fein would at one level doubtless enjoy the spectacle of a subsequent leadership battle.

Unionism is running out of strong leaders with any obvious capacity to unite Protestant opinion, which is so splintered that it is represented by at least six political parties. In this view republicans simply chuckle on the sidelines while Unionism once again displays its disarray.

But for all that there is hope in London and Dublin that significant progress on guns is possible. The idea is that the IRA and Sinn Fein may come up with concessions, not to save Mr Trimble but to rescue the Good Friday Agreement.

The Agreement has been good to the republicans: it has kept them centre-stage, it has made Mr McGuinness the Minister for Education, and it has produced more and more votes. Even the Assembly, which republicans used to say they did not want, has proved an excellent vehicle for them.

The new institutions are popular both with republican leaders and with the Catholic grass roots. The entire peace process need not collapse if Mr Trimble fell, but the Assembly probably would. Things would not necessarily be back to square one, but it could be years before similar institutions were re-established.

It is this self-interest that provides the strongest argument for the theory that republicans may conclude that the time has come for a fresh move. They have invested much time, credibility and effort in the Agreement. Now, perhaps, they will act to protect that investment.