There has been something of a balance of anguish for Northern Ireland politicians of late, as both republicans and loyalists have been bringing themselves to the point of making moves which are groundbreaking and risky. Movement has been so slow for the past year that it has at times resembled complete logjam. So many deadlines have come and gone, so many meetings held with no visible result, that the peace process has seemed devoid of momentum.

Yet the new move by Sinn Fein, which is clearly preparing to endorse policing, could well have galvanic results. Gerry Adams has signalled that he will steer the process of doing so through his party's necessary procedures, and his lieutenants are signalling that this will not be a half-hearted affair. Barring some huge upset, Sinn Fein will formally say it supports the police and the courts, will encourage recruits to the police service of Northern Ireland and will take part in all policing structures.

In republican philosophical terms these are breathtaking commitments. They are all, however, absolutely necessary if Sinn Fein is to achieve its goal of getting back into a devolved government. The IRA is to all intents and purposes gone: so, crucially, is its weaponry, which it used to kill several hundred police officers. Its leaders have put their faith in politics. That means getting political institutions up and running; that means backing the police.

Sinn Fein's potential partners, Ian Paisley and his Democratic Unionist party, do not speak to republicans. To embark on this new course, however, Mr Adams and his people must have received convincing assurances, via government officials, that Mr Paisley will reciprocate. That means accepting that republicans have left their violent past behind and have transformed themselves into eligible coalition partners. It is hard to know which is the more remarkable prospect, republicans supporting the police or Mr Paisley working with Sinn Fein.

Yet both seem, slowly but surely, to be in prospect. There were various wobbles in recent months: word reached both the authorities and Mr Adams that dissident republicans were contemplating assassinating him. At the same time Mr Paisley seemed taken aback by the emergence of factions within his traditionally monolithic party. But the signs are that both Mr Adams and Mr Paisley have decided to go for it and make possible the once unthinkable.