Downing Street appears to believe that it has just slightly tweaked its policy on Northern Ireland to achieve a modest step forward in the process of implementing the Belfast Agreement.

The problem is that the world is beginning to believe that we are witnessing a radical policy reversal, and that the possibility of any IRA decommissioning is fast receding. Why has such an impression been allowed to gain ground?

For the rejectionist unionists in the resurgent Paisley/McCartney and Union First camps, there is an easy answer - the British government always capitulates to the threat of terror.

There has never been any doubt that the fear of a renewed London bombing campaign is a massive concern for a British government, especially one that has presided over the early release of so many paramilitary prisoners.

Against this, the fact remains that Tony Blair could have bought off the republican movement at any time in the last few months simply by dropping a hint that Britain might become a persuader for Irish unity. Again and again - in total disregard of the agreement - the Sinn Fein leadership has rather plonkingly sent out this signal to the Prime Minister, but has repeatedly been rebuffed.

The explanation is rather more specific and conjunctural: firstly, the tragedy of the Balkans War has encouraged a passionate, impatient desire for a compensating triumph. How else can we explain the self-defeating timing of the Downing Street move? Any serious attempt to follow a strategy of this sort had to be delayed until after the European election.

The style of the whole operation has been uncharacteristic. The most public relations conscious of all governments has chosen a strange moment to display a Heathesque insensitivity.

No effort was made to explain an apparently sharp shift in public policy.

It seemed to many in Northern Ireland as if a cold and distant emperor had casually shifted his position without regard to some rather haunting and specific commitments.

In reality, the British government still insists that decommissioning remains an obligation - and indeed even seems to believe that the republicans have now accepted it - and that therefore the recent Downing Street document is of minimal significance, allowing a small step towards the formation of a government by a move towards naming ministers.

It appears also that the government was influenced by public opinion surveys indicating surprisingly strong Protestant public support for the agreement: but this support is not an independent variable, it was linked to the prestige of David Trimble, now temporarily damaged by Downing Street itself.

It seems possible that support for anti-agreement (Paisley-McCartney) parties will outrun support for perceived pro-agreement figures (Nicholson and Ervine) on June 10th, the day of the European election.

But after June 10th the old dilemmas will remain. The fact is that the vast majority of the elected unionists enjoy the Stormont Assembly; more importantly, the transitional programme for the new assembly, combined with the final shape of the new North-South institutions, has inclined some anti-agreement Assembly members to give house room to the view that the agreement may not be as constitutionally flawed as they genuinely felt it was last summer.

The view is buttressed by the growing body of academic literature to this effect, contrasting with the absence of sustained argument on the No side. In this key respect, the argument which was won by David Trimble in the referendum campaign remains won.

As Dr Mo Mowlam put it on Sunday: "The old wound over whether Northern Ireland belongs to the Irish Republic or the UK was sealed last year by the agreement and the peoples' vote. Do we really want to see it reopened?"

The fact remains that division and backbiting are at the heart of modern unionism - encouraging the melancholia of a community naturally inclined, as a result of the bitter experience of "The Troubles", to switch off politics anyway.

But for devolution to work it requires a more united and self-confident unionism - to be able to interact with a nationalism which is already self-confident.

Between the conclusion of the European election campaign and the end-of-June deadline, whatever the result, unionism will be faced with the challenge of breaking the habit of a lifetime and opening up a serious debate on political strategy based on rational choice - rather than the nostalgic charm embodied in Lord Molyneaux's Coleraine speech at the Union First meeting at the weekend.

Since the Anglo-Irish Agreement of 1985 unionism has been in crisis, but it is a crisis which is never fully acknowledged and, as a consequence, can never be resolved. A level of debate worthy of "Old Labour", in which the failure to achieve success is based on "betrayal" by certain personalities (in 1974 it was Brian Faulkner, today it is supposed to be David Trimble) prevails.

Mr Trimble bears some of the responsibility for the crisis - the wear and tear of almost three years of constant political pressure are beginning to show.

A senior diplomat much involved in the peace process recently observed that David Trimble was the indispensable figure in the process. "If he even gets a cold for a week, it's a major problem."

Mr Trimble's much-needed break in North America will encourage some reflection on life without his leadership; both in his party and in the two governments there are some who need to take stock of that less than enticing prospect - although to be fair there are signs that the grim reality is already sinking in.

Such a debate will go on in a context in which the IRA may well not have signalled that the war is over. The republican leadership sends out conflicting signals.

But it is worth remembering that in 1922 Michael Collins told two different types of story.

To hardened militants like James Malone he promised a renewed war to achieve "full freedom", whilst others like P.W. Kenny were told that such a war could not be won.

Today, few doubt that it was Kenny, rather than Malone, who was getting more of the truth. What if something similar is happening today?

Paul Bew is professor of Irish politics at Queen's University, Belfast