Three men hold the fate of Iraq in their hands - and the stakes remain high

If ever one man's journey resembled a desperate last throw of the dice, it was the passage from Basra to the holy city of Najaf undertaken yesterday by the Grand Ayatollah Ali al-Sistani. For three weeks, Najaf had been under siege from US and Iraqi forces, trying to end the revolt of the Shia imam, Muqtada Sadr. Three previous efforts by the interim government in Baghdad and by Sistani surrogates to end the revolt peacefully had collapsed. Old and ill, Shia Islam's most senior cleric was now travelling to Najaf in person. For the Shia faithful, there was no higher authority than his.

If ever one man's journey resembled a desperate last throw of the dice, it was the passage from Basra to the holy city of Najaf undertaken yesterday by the Grand Ayatollah Ali al-Sistani. For three weeks, Najaf had been under siege from US and Iraqi forces, trying to end the revolt of the Shia imam, Muqtada Sadr. Three previous efforts by the interim government in Baghdad and by Sistani surrogates to end the revolt peacefully had collapsed. Old and ill, Shia Islam's most senior cleric was now travelling to Najaf in person. For the Shia faithful, there was no higher authority than his.

The Najaf that received the ayatollah was a powder keg; the slightest spark could have caused a conflagration. A mortar attack destroyed the central shrine in its twin-city, Kufa, as he was en route. Mayhem broke out in the throng of pilgrims making their way to join his procession; many were killed and injured by gunfire. But Ayatollah Sistani's arrival was also accompanied by welcome signs of restraint. Iraq's interim Prime Minister, Iyad Allawi, declared a 24-hour ceasefire; the US suspended hostilities. Late in the evening, after several hours of talks, Ayatollah Sistani announced "a very positive agreement".

It has to be acknowledged that the peace plan announced last night appears to differ little from the terms that were offered by Mr Allawi before. It calls for Najaf and Kufa to be declared weapons-free cities, for all foreign forces to be withdrawn, for security to be left to the Iraqi police, and for those harmed by the fighting to be compensated by Baghdad. But there is one crucial difference: the agreement carries the personal imprimatur of arguably the most venerated figure in Iraq: Ayatollah Sistani.

The immediate question now is whether this agreement will hold, and specifically whether Muqtada Sadr retains sufficient authority over his Mehdi army to cede the Imam Ali shrine which they had made their headquarters. This most sacred of Iraq's Shia shrines had become the ultimate symbol of Sadr's strength. Losing it could diminish him in the eyes of his followers. The risk is of a Mehdi army on the loose.

On the other hand, if control of the shrine is surrendered peacefully, and intact, to Ayatollah Sistani, this would constitute a personal triumph for him and enhance his authority accordingly. More to the point, it would mark an institutional victory for Mr Allawi's interim government, increasing the - still slender - prospects that Iraq can remain a united country and advance towards elections. The removal of the shrine from contention is a first condition for lessening the violence in Iraq. If Mr Allawi was to enjoy even a modicum of credibility, he had to end Sadr's challenge.

The interim government's reluctance to authorise the use of all-out force to capture the shrine was a pragmatic choice, but a wise one, requiring a degree of patience and restraint that has been in lamentably short supply in Iraq. Declaring ultimatum after ultimatum, Mr Allawi nonetheless refused to order troops to breach the perimeter of the shrine. He must now use the time he has won to good purpose and build on the political capital he has gained.

The peaceful surrender of the shrine, if it happens, however, would not necessarily mean that Sadr's uprising is over. The siege has cost hundreds of lives and will leave much resentment and deep psychological scars behind. The popular grievances that Sadr has been so adept at exploiting will have to be addressed, lest they find expression in other, more violent and anarchic, forms. Nor is there any guarantee that, even in dignified defeat, Muqtada Sadr will be persuaded to join the national consultations on elections. So long as he remains aloof, he threatens this process.

Three individuals - Ayatollah Sistani, the interim Prime Minister, Iyad Allawi, and the troublesome imam, Muqtada Sadr - now hold the fate of Iraq in their hands. One costly crisis appeared last night to have been averted. There will doubtless be many more to come.