Leading article: Farewell to arms - and to all criminal activities

In this terrorism-plagued world, with the immense tribulations facing London, Leeds and now Birmingham, it is a small but distinct relief to hear of one conflict that is winding down rather than escalating. The news from Belfast is that the IRA is now prepared to give up its guns and leave terrorism and criminality behind, enabling Sinn Fein to pursue republican aims through politics alone.

In terms of Irish history, this is a wondrous thing, since for centuries violence has been an integral part of the republican psyche. The idea that republicans can finally detach themselves from their "armed struggle" is truly historic. Republicans have pulled off the very difficult trick of maintaining their aims while changing their methods: quite a feat for a movement whose goal, Irish unity, is hardly even on the horizon.

Gone is its futile quest for victory and a forced British withdrawal, regardless of the wishes of anyone else in Ireland and Britain. Compromise and negotiation is the new path, and has already delivered political dividends for Sinn Fein in both parts of Ireland. No one will be congratulating the IRA for discarding a terrorism it should never have embraced. When the troubles boiled over in the late 1960s, many who would never otherwise have been caught up in violence were affected.

That could be understood, if not condoned, and republicans were not the only source of violence. But the IRA then persisted in waging a "long war", far beyond the point where its futility had become obvious to all. The ceasefires of 1994 and 1997 were important turning-points but, although they ended IRA killings of security personnel, criminality such as "punishment" attacks, robberies and the like, continued.

The IRA's exact 1994 wording was a declaration of "a complete cessation of military operations", a formulation which turned out to mean that it felt free to indulge in lower levels of violence. This time, it has been made perfectly clear to republicans, both privately and publicly by the British and Irish governments, that there can be no such lethal linguistic loopholes. They have to signal in plain language that it's over: no more cynical semantics.

Two promises are absolutely necessary: one is to carry out full arms decommissioning, and the second is to desist from law-breaking. But these are first rather than final steps, for republicans have major credibility problems. Gerry Adams, for example, says he was never on the IRA's army council, or indeed in the IRA at all. Sinn Fein and the IRA say the IRA did not rob the Northern Bank in Belfast of £22m before Christmas. Since few believe a word of this, new IRA promises must be subjected to the most exacting scrutiny. It will take months for reliable confirmation to emerge that the guns have gone and that illegality has ceased.

A farewell to arms and to criminality will be a highly worthwhile advance in itself, but the further hope is that it will open the way for fresh political negotiations. The timing of these is largely dependent on the Rev Ian Paisley, who has electorally banished all rivals and is the undisputed leader of Ulster Unionism. His scrutiny of republican behaviour will be more exacting than anyone else's. Since one of his favourite sayings is that leopards do not change their spots, he will probably take months to concede that republicans might have had a meaningful change of heart. The road ahead is thus strewn with difficulties.

Yet, unlike so many other conflicts, this one gives every appearance of subsiding; and now it has a road map which holds out the prospect of further gradual progress.