A nasty reminder that the IRA should hurry up and start decommissioning

It was, as Alan Fry, the head of Scotland Yard's Anti-Terrorist Squad said, "an evil act". Cowardly as it was, however, it is not difficult to work out why the so-called Real IRA placed a bomb in Ealing Broadway. The terrorists' aim is quite simple, and obvious – they want to destabilise and, if possible, to destroy the Belfast agreement and the Northern Ireland peace process.

The timing of the bombing, straight after the latest attempt by the British and Irish governments to move the process along, was hardly a coincidence. The Real IRA wants to remind mainstream republicans that the agreement does not amount to a united Ireland, that the lives sacrificed to the cause have been, in their view, in vain. They also want the Unionists, whose patience is already sorely tried, and the British government, to question the value of a process that allows terrorist prisoners to be released, and, as Unionists see it, undermines the RUC and the security forces, and yet does not deliver what is supposed to – an end to terrorist violence.

The fear is that the Ealing bomb may mark a change of tactics and a stepping up of the dissidents' campaign on mainland Britain. Leaving a bomb near a pub is a particularly cold-hearted act, even by their debased standards. Seven people were injured, but the damage to life and limb could easily have been much more grievous. It is chillingly reminiscent of the Guildford and Birmingham pub bombings and other outrages perpetrated by the IRA in the mid 1970s.

It would be surprising if those thoughts have not run through many minds since the Ealing bomb. Yet we should also be clear that if the Omagh outrage of 1998, which left 29 dead and some 300 injured, did not destroy the peace process, then neither will the Real IRA's latest campaign. Indeed, there is some evidence that the shock of Omagh impelled the parties to speed up their work.

There is a determined and stubborn fragment of republicanism whose addiction to violence is so acute that they will probably never give up the bomb and the bullet. Similarly, some of the most extreme loyalist terror groups like Red Hand Defenders will never be reconciled to the methods of democratic politics. They too will probably continue their intermittent sectarian murders of the innocent. It does not matter to them that the vast majority of the people of Ireland, north and south of the border, have rejected, indeed abhor, their methods. The only comfort is the hope that the more outrageous the activity on the periphery, the more the political centre will cohere.

Even so, the work of the Real IRA and the other splinter groups is a potent reminder that the threat of paramilitary violence is a very real one, and it blunts Sinn Fein's complaints about the British security forces' installations in Northern Ireland, and their demands for the "demilitarisation" of the province.

In any case, the more isolated the terrorist groups are, and the more the politicians engaged in the peace process demonstrate that there is a better way, the more chance there is that the activities of dissident republicans and loyalists will be curtailed, even if they may never be completely eradicated. And that means progress and compromise between now and Tuesday, the deadline for the parties to respond to the Blair-Ahern document. Central to that, in turn, is for the IRA to make some concrete gesture on decommissioning over the next few days.

No single act would do more to restore faith in the peace process. It is needed now more than ever. The IRA know what they have to do; there must be no more delay.