A terse IRA statement, which some believe may be the last ever to be issued by the organisation, said the process of putting arms beyond use had been completed. Its assertion was supported by the Canadian decommissioning expert General John de Chastelain, who said he, together with a Catholic priest and a Protestant minister, had spent "many days, long days", witnessing this.
They had watched, they said, as IRA members put out of commission large amounts of arms and explosives, ranging from rifles to heavy material including flame-throwers and surface-to-air missiles.
The general and the two clergymen asserted their firm belief that "the totality of the IRA's arsenal" had gone. They also indicated, however, that no one was precisely sure how much weaponry the organisation had possessed.
Their message was that decommissioning was an inexact science littered with complexities. But they insisted that the material they had seen being rendered unusable was consistent with security estimates of the IRA arsenal.
The general gave some logistical details. Some ammunition was still in its original boxes, while some was in belts and some was loose. This, he felt, verified intelligence reports that IRA members had spent weeks "scouring the country", collecting weapons from far and wide.
But the IRA was itself unsure how much it had, he said, and some could not be traced: some of its members had, for example, died without revealing where they had stashed their guns.
The bulk of the arsenal had been made up of weaponry given to the IRA in the mid-1980s by Gaddafi's Libyan regime, including major weapons which were capable of downing helicopters and aircraft.
But these weapons, fearsome at the time, have now aged - "much of it is very old", the general said. It has been said that the IRA is jettisoning its guns because they are politically obsolete: he seemed to confirm that many were physically obsolete also.
The general was unable, under legislation, to say exactly how much weaponry had been rendered inoperable, but a colleague added: "It really is an immense amount."
The potentially momentous step generated a mixed reception, ranging from a warm welcome in London and Dublin to continuing deep scepticism and doubt in Unionist quarters.
The Rev Ian Paisley's Democratic Unionist Party found instant fault with the announcements, complaining that the decommissioning had not been transparent, that no inventory of weaponry had been given, and that the general had expressed trust in the IRA.
Mr Paisley accused the two governments and the IRA of "duplicity and dishonesty".
These varied reactions meant that, as so often in the Irish peace process, a highly significant event was shrouded in clouds of cynical mistrust rather than being universally accepted as a breakthrough.
Mr Paisley will therefore, as expected, remain a doubting Thomas, his demand for photographs of the decommissioning having been rejected. This was, in any event, just the second of three phases of the IRA fulfilling its pledge to go out of business. In July the organisation made its promise; now it has said, to the evident satisfaction of the British and Irish governments, that it has fulfilled that promise.
The Democratic Unionists, as ever, will not be so readily satisfied, but the party and the Protestant population will now probably take some weeks to reach a considered conclusion on whether it can rely on the assurances of the general and the churchmen.
But it will take many months for Unionist leaders and grassroots to develop real confidence that the IRA has actually gone out of business. That third phase will take time, and a continual process of verification.
There will be reports from a monitoring commission which includes figures from Britain, Dublin and Washington. And unless they give republicans a clean bill of health, confirming that the IRA really has become inert, the peace process will stay in its present state of deadlock.
In the meantime there was no carnival atmosphere in Belfast yesterday. Protestants and Unionists have a deep-seated suspicion at times such as this: perhaps, some of them think, it is all a bluff. A majority certainly welcome the idea of a disarmed IRA, but fear that republicans will be rewarded with substantial concessions.
But many in Northern Ireland and elsewhere will take huge heart from the fact that a once-deadly paramilitary group has gone into voluntary liquidation. It killed around 1,800 of the 3,700 dead of the Troubles, indelibly associating Ireland with murder and mayhem. As the statistics show, it was not the only source of violence, but it was the main one, and the most formidable of the terrorist groups.
Mr Paisley and others may maintain for some time that it may have held back some weapons, or that it could rearm itself. But those who observed this act, both General de Chastelain and the clergymen, were clearly mightily impressed by what they experienced.
The reason why the IRA feel able to ditch their weaponry is because they have fashioned Sinn Fein into an effective political force, north and south of the border. Sinn Fein wants to get into government, both north and south of the border, and in Belfast the only way to achieve this is through a deal with Ian Paisley. The next phase of politics in Northern Ireland will centre on efforts to persuade him that it safe to cut a deal with the republicans.
This could be a long wait. But in the meantime, many observers will ponder this new move and conclude that, whatever problems lie ahead, the chances of reaching a more peaceful and more stable Ireland have been enhanced.
"There was complete failure from General de Chastelain to deal with the vital numbers ... We do not know how many guns, the amounts of ammunition, explosives - nor were we told how the decommissioning was carried out."
The Rev Ian Paisley, leader of the Democratic Unionist Party
"Successive British governments have sought final and complete decommissioning by the IRA for over 10 years ... Today it is finally accomplished. And we have made an important step in the transition from conflict to peace in Northern Ireland."
"I don't see how anyone can say if all the IRA's weapons have gone, but either way it was substantial and you have to recognise that. The Rev Harold Good is a man of integrity and as he said, why would the IRA lie?"
Alan McBride, whose wife was killed by an IRA bomb in 1993
"It's a landmark development, it's of real historic significance, the weapons of the IRA have gone and they're gone in a manner which has been witnessed and verified ... We are enormously relieved that we can finally close this difficult chapter of the peace process."
Irish Premier Bertie Ahern
"Decommissioning is important, but it is only one element of what is needed ... People will now want to see clear evidence that all forms of paramilitary and other criminal activities ... have ended for good."
Shadow Northern Ireland Secretary David Lidington
"I hope that these developments will help to bring about a better climate in which trust between the two communities in Northern Ireland can flourish in the years ahead and that it will herald a speedy end to all ongoing paramilitary activity."
Irish President Mary McAleese