Even if the IRA declares that the war is over, the Unionists won't believe it

Sinn Fein is able to deliver what it promises. It is not a party where dissenters run to the newspapers to denounce the leadership

Seen from the trembling borders of the Middle East the old quarrel has never looked more pointless, its details never more arcane, the steeples of Fermanagh and Tyrone too dreary for contemplation. The cities of the Arab world are seething and fearful. When 100,000 people rally in Cairo the numbers may seem puny compared to the million who marched in London. But the political significance of a demonstration of that size – barely reported in the Western media – should not by missed. There will be a war within weeks. This war will shape the future not only of the Middle East, but also of the institutions and laws that have sought to direct international relations since the Second World War. No way could the stakes be higher.

But on Monday Tony Blair will leave the planning of that war to others, while he flies to Hillsborough Castle outside Belfast for talks on the Irish peace process. We are told the talks might even drift into a second day. Those with a taste for irony will reflect that while Mr Blair is limbering up to disarm Iraq by force he is attempting to persuade the IRA to give up its weapons peacefully and go into retirement.

The difference, Mr Blair would doubtless say, is that the IRA is serious about disarming. The problem is that most Unionists' position on the IRA is roughly akin to that held by Mr Blair and President Bush on Iraq. The Unionists refuse to believe the Republicans are sincere and cite breaches of the ceasefire – punishment shootings, targeting and intelligence gathering – to justify their militant scepticism.

The Republicans argue that what has been achieved since the IRA ceasefire back in the 1990s has been miraculous. The war against the security forces is to all intents and purposes over. There is a power-sharing agreement, albeit one whose institutions are suspended. The problem is that the war of mistrust and fear is as bad as ever. Neither Republicans nor Unionists can walk away from their responsibility for this. The former has taken too long to give, while the latter has been relentlessly negative in its reaction to any concessions. Let me deal with the Republicans first.

The movement headed by Gerry Adams and Martin McGuinness is politically stronger than at any time in its history. Peace has produced a substantial electoral dividend. Traditional constitutional nationalism in the form of the SDLP is struggling to hold its own against a highly organised and aggressive political machine.

When it comes to political negotiations the Sinn Feiners have been united and very, very smart. They have also had the distinct advantage of being able to deliver on what they promise. This is not a party where dissenters run to the newspapers and airwaves to denounce the leadership. By the time Adams and co arrive at talks, the parameters of any concessions have been well worked through and agreed. So the positive murmurs of the kind currently emanating from the Republican camp suggest we should get ready for a significant IRA declaration.

For Mr Blair this will have to include verifiable pledges that the IRA will cease recruiting, gathering intelligence, shooting teenage boys for "anti-social" behaviour and that it will engage in serious decommissioning of weapons. The long anticipated "war is over" announcement is also in the works. When you see an influential group like the National Committee on American Foreign Policy call for decommissioning and a verbal declaration of the war's end, you realise the endgame is in sight. Even more significant the group is calling for Sinn Fein to give "unconditional support" to the police. The leading figure in that group, Bill Flynn, was the man who secured Gerry Adams's first US visa back in 1993. The post-11 September American world view leaves no room for organisations linked to or remotely soft on terrorism.

In return Mr Blair is being asked to deliver a package of measures which – in the language of Sinn Fein – would "demilitarise" Northern Ireland. This means scaling down the number of troops and patrols, dismantling more watchtowers and barracks and restructuring the control of policing, for example a new security ministry which would have nationalist and Unionist ministers of equal status working alongside each other. More controversial will be a plan to allow wanted Republican activists to return home "under licence". But it's the kind of measure Adams knows is very useful in bringing the IRA Army Council to agree effectively to disbanding.

So the deal is there for the making. But let us presume the Republicans and the British government do agree. Where does that leave David Trimble, the isolated and besieged leader of the Ulster Unionist Party? Still marooned up the River Lagan without a paddle is the glib response. With a party grassroots that has been infuriated by the sight of the likes of Martin McGuinness visiting schools as Ulster's Minister of Education, Mr Trimble has found direct rule from Westminster a relief. The agonising moments of choice that cropped up repeatedly during his tenure as First Minister were put on hold. Now he is about to be confronted again. If he goes with a deal that brings the agreement back to life he will be damned by the hardliners for whom the very idea of Sinn Fein in government is a nightmare. If he says no it won't please them anyway.

Support for a moderate Unionist position has been draining away since shortly after the Good Friday Agreement was signed. It will be dealt a potentially killer blow at the Assembly elections due in May, when Ian Paisley's DUP is expected to trounce Mr Trimble's party. The optimists believe that would then lead to a complete realignment of Ulster politics; Sinn Fein and the DUP would come together and hammer out a new deal. I just can't see it myself.

So what is the point of next Monday's summit if it all looks like falling apart at the polls in May, or before then if David Trimble is overthrown by his own party? I was pondering this grim proposition when I came across an article in the current edition of Fortnight, the periodical of Ulster's thinking classes. A South African academic, long resident in Belfast, Adrian Guelke, suggested that rather than go for Assembly elections with all their party political bitterness, the Government should either delay the elections (to give people time to take in and appreciate the IRA concessions) or hold another referendum.

"The referendum in 1998 brought to the polls voters turned off by the nature of party-political competition and maximised the turnout of moderate voters," wrote Guelke. I believe Guelke is correct. Holding elections in the current atmosphere would be perilous. A referendum would be marginally less so, but it stands a greater chance of restoring the ascendancy of Ulster's middle ground. And even with the anguish in the Middle East, all of this matters like life and death.

The writer is a BBC Special Correspondent