July 1st is an Ulster deadline. It was, before the revised calendar, the date of the Battle of the Boyne. It was the first day of the Battle of the Somme in 1916. But this July 1st deadline, which may well decide the future of the Belfast Agreement, was not set by Mr David Trimble, but by the governments in London and Dublin.

On May 5th last year the two governments declared June 2001 the deadline for full implementation of the agreement, including the resolution of the decommissioning issue. It was that commitment which opened the way for the working of the Assembly, the Executive and the cross-Border institutions. Failure to meet the deadline, the governments stated, would lead to an immediate formal review of the agreement.

Ever since, Mr Trimble has been aware, even if both London and Dublin seemed determined to forget it, that time was running out for the agreement and the institutions set up under it unless decommissioning by the IRA took place. The statement of last May 5th specified no date in June. In the event, the general election on June 7th has obliged Mr Trimble to issue a public reminder of the deadline, setting it for the end of the month.

It was hard to see how Mr Trimble and his Ulster Unionist Party could survive the poll if no substantial IRA move on arms had taken place before it. Mr Trimble himself could be unseated in Upper Bann; his party at Westminster could do so badly that the Assembly party could split, or be forced to withdraw its support from the agreement. Mr Trimble had to move ahead of the poll to avert disaster.

None of this should surprise or shock; the threat to the agreement comes not from the innate wrong-headedness of the majority population in Northern Ireland but from the manifest failure to implement its most fundamental element. That is the establishment of an absolute commitment to exclusively peaceful means by all parties, evidenced by, in the agreement's words, the total disarmament of all paramilitary organisations. That was to happen within two years, since extended to three, hence the revised June deadline.

The two governments have soft-pedalled on the deadline. Last week, the Secretary of State, Mr John Reid, presenting a three-year balance sheet on the agreement, managed, incredibly, to make no mention of the deadline. The Taoiseach, in his Arbour Hill speech eulogising Pearse and the 1916 Rising, said the agreement was broadly intact, and he was confident it would survive the election. He did say urgent issues needed to be resolved by June, the main one, he seemed to indicate, being policing. He also said it was in everyone's interests that "further early progress be made in putting arms beyond use".

His choice of priorities and language, plus Mr Reid's comments, hardly indicated any resolve on the part of the two proprietors of the Belfast Agreement to rescue it by a concerted drive to achieve what was probably the only thing that could do so - the total disarmament of all paramilitaries by next month.

It is commonplace among the worthy in Belfast that this "obsession" with decommissioning is unfortunate if not incomprehensible. Events have combined to make such lofty wisdom less and less likely to appeal to voters.

Republicans continue to plant bombs, the rail services are disrupted, punishment beatings occur almost nightly. Last week a man was shot down in the centre of Belfast by assassins, who, it is generally assumed, were both armed and mandated by a paramilitary organisation, most probably that to which ministers in the Northern Ireland Executive are still, according to the Prime Minister, inextricably linked. The venomous and somewhat misplaced triumphalism of IRA relatives after the Strasbourg ruling did not help.

The admission by one of those ministers that he was number two in the IRA in Derry in the early 1970s and must therefore, presumably, have authorised or assented to the succession of murders committed by the IRA in the city in that period, may not have been news to anyone, but it again raises crucial questions over the implementation of the agreement.

Mr McGuinness has never given any indication that the IRA actions in 1972, or since, were wrong. He has never said that the IRA has no right to exist, or to resort to arms, yet the agreement has put him into ministerial office in an Executive theoretically opposed to even the threat of violence.

Many of those who voted for the agreement in 1998 did so because it offered the chance of an end to violence - not a respite, or a decline to "an acceptable level", but a final and total rejection of it by those hitherto claiming a right to use it for political ends. That, it was felt, was the real core and purpose of the agreement, of necessity couched in a mixture of code and fudge, and accompanied by many goodies for those ready to make this historic transition. No Damascus Road conversion was demanded, no instant public repentance; two years were allowed and a generous smoke-screen provided.

Some of those who voted yes had no expectation that the IRA would give up its arms, but neither did they expect that, three years on, Sinn Fein would be in government, with the IRA still armed and still active. (They had Mr Blair's written promise that this would not happen.) To persuade them to vote again for pro-agreement candidates will take more than words from the IRA, or assurances from the Independent Commission, or, indeed, the cementing over by the IRA of some of its arms dumps.

Mr Trimble may, as ever, be in the front line, but the real judgement on June 7th will be on the implementation of the agreement by Mr Blair and his pal in Dublin.

The agreement does not have to fall; Mr Blair and Mr Ahern may just have to choose between it and Sinn Fein. It may be impossible to have both.

Dennis Kennedy is a Belfast-based academic and political commentator