Republicans must act to show their commitment to the peace process

The concept of the moving brink is familiar in the politics of Northern Ireland. The brink was going to be today's meeting of the ruling council of the Ulster Unionist Party, but no challenge to David Trimble's leadership emerged. Then it was going to be Mr Trimble's threat to resign as First Minister next weekend. If there is no movement from the IRA on decommissioning its weapons, he will still resign, but the Government may prevent the crisis turning into a drama by suspending the Northern Ireland Assembly or otherwise delaying the point at which his resignation takes effect.

That is not to say that the situation is not serious. The rioting in the Ardoyne district of Belfast this week was a reminder of the hatreds which still seethe, never far below the surface, in Northern Ireland. The trigger for this latest outbreak of violence, a display of loyalist flags outside a Roman Catholic school, remains as bafflingly alien as ever to those of us on the mainland. It is a warning that, although great progress towards normality has been made since the Good Friday Agreement three years ago, the danger of sliding back into the cycle of violence has not gone away.

It should be clear, however, that Mr Trimble was right to issue his postdated letter of resignation. Despite the unfortunate Hitlerian tone of his declaration that "my patience is at an end" in Downing Street at the start of this week, it is true that his situation has become intolerably difficult. That was underlined by the poor showing of the Ulster Unionists in the general election, in the one part of the United Kingdom where turn-out did not fall.

Tony Blair, on the other hand, is equally right to try to sustain him. It is a hopeful sign for the long term that Ian Paisley's Democratic Unionist Party has modified its absolute opposition to the Good Friday Agreement, calling instead for parts of it to be renegotiated. In the meantime, however, it is important to demonstrate the Government's support for the one person who can keep the power-sharing show on the road.

Once again, the imperative weighs on the republican side to ensure that the brink keeps receding into the middle distance. Sinn Fein made strong gains in the general election; it has most to lose from the collapse of the Assembly; and its supporters, according to the opinion polls, are more in favour of decommissioning than ever before.

The republicans, therefore, are able to move. Just as important, however, they are under a powerful moral obligation to do so. Their leaders signed up in the Good Friday Agreement to a promise to use their best endeavours to secure IRA disarmament by May last year. It is disingenuous for Gerry Adams and Martin McGuinness to complain about the lack of progress on reforms of policing and winding down the more obtrusive forms of the British military presence. The republicans have got a great deal out of Good Friday Agreement, and have given much too little ground in return. Of course, opening up some arms dumps to international inspection was a highly significant symbolic gesture – fairly warranting the "seismic shift" description applied to it by the Prime Minister. But the third inspection, a week before the election, did not constitute a step forward: it was the mere consequence of the original decision.

It is now time for the IRA to move beyond that gesture and put some of its arms permanently beyond use. Recent history shows that the republican movement will move, but only under extreme pressure, at the last minute and to the smallest degree necessary. It took the suspension of the Northern Ireland Assembly to produce the last big shift at the beginning of last year. If it has to take another suspension to force the republicans to deliver, then so be it, but if the republicans want to demonstrate their commitment to the democratic process, they should jump before they are pushed.