There have been a number of occasions when events relating to the Northern Ireland peace process have fallen apart at the final press conference. This was emphatically not the case yesterday. General John de Chastelain and his colleagues were far more detailed in describing the character and the extent of IRA decommissioning than they have ever been before and the two independent witnesses, notably the Rev Harold Good, a former president of the Methodist Church in Ireland, were eloquent and compelling. This act of disarmament may have come seven years after the Good Friday agreement, and the delay may have diminished its impact. Yet it has happened. This is an immensely important move.

By itself, however, as both Tony Blair and Bertie Ahern, his Irish counterpart, rightly indicated, this is not the end of the issue. The International Monitoring Commission (IMC) will report next month on the broader activities of the paramilitaries, including the IRA, and will publish a further review in January. It is crucial that every aspect of criminality has been eliminated and there can be no return to devolution until that has happened. If, as is probable, the commission awards the IRA a clean bill of health not once but twice, the logic of attempting to restore the institutions of the Good Friday agreement is irrefutable. It would be bizarre to prevaricate any longer.

The question then is what the Unionists, particularly the Democratic Unionist Party (DUP), do in return. The response of the Rev Ian Paisley and his party to IRA decommissioning could have been one of quiet satisfaction or even noisy triumphalism. The DUP has, after all, long called for the IRA to place all its arsenal “beyond use” and was the first in the Province to argue that devolution constituted the solution to the Troubles. Any reasonable observer would contend that it should take “yes” for an answer. That does not appear to be the DUP’s instinct. It has implied that either the IRA decommissioning did not occur (and that men such as General de Chastelain and Mr Good are liars or fools), or that it was only partial, or that it happened but in an unsatisfactory way because of the lack of photographic evidence. These are not credible positions. There are, of course, doubts whether every bullet has been destroyed, and the IRA is rich enough to replenish its stockpile at a later date if it wishes. This would have been true if the decommissioning process had been photographed, or Mr Paisley had been a witness. Unionism will seem implausible if it fails to react rationally.

It will also render itself irrelevant. If the DUP chooses early next year to sit on the sidelines, despite the solemn testimony of the Independent International Commission on Decommissioning and the IMC, the peace process will continue without it. A strange form of direct rule will start with nationalists in the driving seat and the slogan of the DUP, ironically, becoming less “No surrender” than “Ourselves alone”. It is hard to see how this helps the Unionist cause and it is a perverse stance to take when the IRA has disposed of its arms and Sinn Fein is lobbying for the revival of the Stormont Assembly. Decommissioning demands repositioning. The Unionist community has four months before it is likely to be confronted with this matter. It has to deal with reality. It must now come in from a very bitter cold.