Yogi Berra, the American baseball icon who coined the immortal dictum: "When you come to a fork in the road, take it", would approve of the work of the British and Irish governments last week. When faced with tough realities they tried to have it both ways.

The Hillsborough declaration tells us on one hand that decommissioning is no longer a precondition, but on the other that some disposal of arms must occur by a certain date in order for Sinn Fein to join the executive. It also states, paradoxically, that while decommissioning is an obligation it is also voluntary.

Clearly the governments were hoping their sleight of words would allow some of the inherent contradictions in the peace process to be elided once again, and a new plateau reached by the formation of the executive in return for some arms being placed out of use.

There is nothing wrong with such a tactic given that there is constant parsing and analysis by all sides of every document issued by the two governments in Northern Ireland. In that context, it is understandable that Mr Blair and Mr Ahern would seek to maintain an even keel and have both sides take comfort from different aspects of official statements. The Belfast Agreement was a masterpiece of such balance.

On this occasion, however, the fudge-meisters have failed in abject fashion to weave their spell. The Hillsborough declaration, far from moving the situation forward, has propelled it backwards to a point where it could easily yaw out of control.

What went wrong? There appears to have been a collective failure by the two governments to comprehend the psychology of the republican movement. The Hillsborough declaration contains much of what could be workable, but it presents the IRA with an ultimatum to put arms out of use by a May deadline. It also moves outside the Belfast Agreement, the Rosetta stone for republicans of their involvement in the peace process.

The ultimatum on arms was given despite the private and public entreaties by Gerry Adams and Martin McGuinness that they could not deliver weaponry from the IRA in such circumstances. Amazingly, it seems, the governments decided to go ahead anyway.

The Sinn Fein leaders knew that ultimatums are guaranteed to stiffen the spine of republicans like almost no other tactic. Though this particular one is couched in velvet-glove language it contains, nonetheless, the clear threat that if they do not respond they will face being shut out of power.

The decision to move outside the framework of the Belfast Agreement in the declaration is also hard to fathom. The failure to launch an all-out push over the past year for the implementation of an agreement voted for by 71 per cent of the people in the North and 95 per cent in the Republic, and to allow it to be utterly side-tracked by decommissioning, will puzzle future historians.

Judging by their Easter Sunday orations, republicans have already deconstructed the Hillsborough declaration as meaning that despite the Belfast Agreement and their hard-won ceasefire, their future role in government is totally dependent on bowing to the key unionist demand of arms hand-over. Further down the road they see the ground being prepared for them as the fall guys if the process comes apart.

That may appear an overly harsh reading of the declaration, but it is undoubtedly the view that is prevailing in republican circles. A leading Sinn Fein official told me his phone had rung constantly early on Friday morning with disgruntled party members furious at the perceived ultimatum on decommissioning.

Perhaps the two governments were lulled by the success in the past that Sinn Fein leaders have had in selling to their movement the many steps towards political involvement, including the cease-fires, the removal of Articles 2 and 3 and participation in what they regard as a partitionist assembly in Stormont. "I think we are victims of our own success," a leading republican told me ruefully in Belfast on Friday.

But they are not miracle workers. They are simply not able to sell decommissioning on whatever pretext under the shadow of an ultimatum, or outside the two-year framework of the Belfast Agreement.

Nor will they attempt to, in my opinion, as to do so could precipitate a split which would have enormous consequences for everyone on the island. The republican movement is still in transition from physical force to solely political activity. It is a fraught process, not helped now by ill-advised pressure tactics.

Nor are they likely to be rushed into making such crucial decisions. For a year, they believe, they have seen the two governments wait for David Trimble at every remove, constantly postponing deadlines as the Ulster Unionist leader erected obstacles.

They are unlikely to oblige Trimble and the governments now with any rush to meet the latest deadlines. "We lived up to everything we signed up to on Good Friday, and we have had the year-long unionist stall, and we are now being asked to pay the price. There is a deep sense of outrage about that," a leading Sinn Fein official said.

But there is also something more serious arising out of last week's developments. Internally, the Sinn Fein leadership now faces the spreading belief that the Irish Government has abandoned them for a dangerous liaison with David Trimble and the wilder shores of unionism.

The major progress in the peace process came when Dublin, SDLP and Sinn Fein were able to agree elements of a common strategy. That is where the IRA cease-fires, the bedrock of the peace process, have come from. The times of difficulty have come, as now, when Dublin appears to have gone off on the old SDLP/Ulster Unionist/British government tangent, which failed to bring any permanent measure of peace for a quarter-century.

Fergus Finlay's famous comment that the peace process without Sinn Fein is not worth a penny candle still holds true today.

Bertie Ahern secured an IRA ceasefire within weeks of gaining office and did a remarkable job negotiating the Belfast Agreement, so much so that Senator George Mitchell in his new book nominates him as the hero of that agreement. Perhaps he sees a way forward from this declaration, but the ill-concealed anger in republican circles last weekend will be very difficult for him to salve.

These are, undoubtedly, trying times in Northern Ireland and there is undoubtedly a weariness with the decommissioning issue that straddles all perspectives and parties. However, the first maxim for government leaders should be to do no harm, if they can't do good. That, unfortunately, does not appear to be the case in this instance.

Niall O'Dowd is publisher of the Irish Voice in New York