The brutal murder of 22-year-old Charles Bennett, whose body was found on waste ground off the Falls Road last Friday, has cast a dark shadow over the peace process. It is now admitted that Mr Bennett was shot by the Provisional IRA. Republican sources, quoted by Suzanne Breen in this newspaper yesterday, claimed that this was done "to reassure" discontented hard-liners within the ranks. If that really is the case, it adds to the obscenity of this killing.
Taken together with the attempts to smuggle guns from the United States, it also underlines dramatically the serious pressures now being exerted on Gerry Adams and his supporters. One republican source told me that, for the first time, grassroots members are openly criticising Mr Adams's judgment and asking what the point is of the move into politics.
It was always on the cards that this was going to be a very difficult summer in Northern Ireland. So it's only proper to note that in some ways - for example the relatively peaceful progress of the Orange marching season - these fears have been confounded. But the failure to agree a power-sharing executive last month, and the delays in setting up cross-Border bodies, have caused deep anger in the republican community and this should not be ignored.
Despite the perceived fraying of the cease-fires on both sides, Bertie Ahern is right to reject John Bruton's demands for clarification on what penalties might be imposed on Sinn Fein and parties associated with loyalist paramilitary groups. Leaders like Gerry Adams and David Ervine are already doing all in their power to preserve peace and prevent a further slide into violence.
To talk of penalising them, at a time when both communities are waiting anxiously for George Mitchell's review of the agreement, only adds to fears that the hard-liners are now in control of the political agenda.
The handling of the peace process in recent months, particularly by Tony Blair but with the co-operation of the Irish Government, has been a major factor contributing to the sense of crisis. For anyone with even the most remote sensitivity to Northern Ireland's politics, it was obvious that David Trimble would not be able to deliver his party's agreement to an executive, prior to IRA decommissioning, at the height of the Orange parades. The setting of a deadline was a serious mistake. It led directly to the farcical scenes at Stormont, the regrettable resignation of Seamus Mallon, and to headlines that the Good Friday agreement was unravelling fast.
That is not the case. Not yet. But the damage done to public confidence in politicians by these events must be recognised, and steps taken to repair it. The Sinn Fein leadership now has to deal with the suspicion among its own grassroots that David Trimble will never share power with Catholics. "His agenda is quite clear," one republican, an unswerving supporter of the move to politics, said to me. "By focusing exclusively on the decommissioning issue to the exclusion of everything else, he can put off having to set up the executive right up to May 2000."
Rightly or wrongly, that is now a suspicion which is as strong in republican ranks as the mistrust of Sinn Fein's commitment to peaceful politics is among many unionists. Gerry Adams explained the effect which this is likely to have in his interview with Miriam O'Callaghan on RTE's Prime Time last week. He referred to "the huge mistrust of politics" which has always existed within the republican movement.
The delays in setting up the power-sharing executive and other political institutions like the cross-Border bodies has fuelled that mistrust. The danger now is not of a full-scale return to war by the IRA, but that he and his colleagues will be seen to have failed. If that happens, and there are signs that it is already happening, then Mr Adams and his supporters will be "lumped together with all the other politicians who have failed" and will be swept aside.
This accords exactly with the gloomy analysis of the situation that one has heard over recent months from dissident republican groups like the 32-County Sovereignty Committee.
The Sinn Fein leader has appealed to Tony Blair to ride to the rescue of the agreement, but the real appeal is to those unionists who want the accord to work. It is time for them to recognise that these fears are real. The more moderate of their representatives, like Dermot Nesbitt, insist that unionists want to see an inclusive executive up and running. Esmond Birnie, UUP Assembly member, was probably speaking for many in the unionist community last week when he said that "this is emphatically not about any unionist distaste for having a Catholic about the place."
My own view, for what it's worth, is that David Trimble is committed to making the Good Friday agreement work and has already taken considerable risks in pursuit of this objective. The unionist leader needs to accept that the anger and mistrust among the republican grassroots represent as much of a threat to Gerry Adams as the equally valid suspicions in his party about Sinn Fein's commitment to politics have been to him.
The danger is that if there are more atrocities like the murder of Charles Bennett, they will be used by Mr Trimble and his colleagues for further attacks on Mr Adams and demands for Sinn Fein to be excluded from the political process.
That would be a dangerous - and potentially tragic - mistake. There is an urgent need to rebuild confidence in both communities that the agreement can and will work. That is a task which should not be left to politicians, who are already under pressure.
The challenge extends to church leaders, business people and other members of civil society. They must argue the case for courage and taking risks, rather than holding back in fear.
It can be done. In 10 days' time it will be the anniversary of the Omagh bombing, when it seemed all hope for progress in Northern Ireland had perished along with the victims of that terrible day. That did not happen. Instead, the virtues of courage and generosity triumphed to rebuild a community which still believes that people can live together in peace.