Concern that the Irish peace process may be in danger of unravelling has been heightened by the fourth violent death in three weeks in Belfast, all of which appear to be the work of the IRA.
The latest victim was Martin McCrory, a 30-year-old west Belfast man, who died after being hit in the chest by a shotgun blast fired through the window of his home in the republican Turf Lodge district on Wednesday night.
His three-year-old son was slightly hurt in the hand in the attack, though Mr McCrory's partner and another son were uninjured. The killing was the sixth in a series of "punishment" killings which stretch back to last April, but the fact that four have taken place this month represents a significant escalation.
Although the Government does not appear to regard the killings as a breach of the ceasefire called by the IRA, security sources say there is little or no doubt that the attacks have been carried out by the IRA or with its blessing.
Three of the dead are regarded as leading drug-dealers. Mr McCrory is reported to have been involved only in minor-league criminal activity. He was known locally as a burglar and joyrider, while police sources said that any involvement in drugs was at most dabbling on a small scale.
The first two killings in the sequence came in April and September, involving big drug figures, and the general impression at that point was that such attacks amounted to a lethal form of "community policing", aimed at preventing a flood of drugs coming into Northern Ireland.
But this month's increased rate of killings suggests that a new phase of IRA activity may have opened.
It is hardly a coincidence that the international body on arms decommissioning, headed by the former US Senator George Mitchell, began work earlier this month and is due to report by the middle of January.
This report will represent a crucial point in the peace process and seen against this background the killings convey the message that the IRA not only intends to keep its weapons but also intends to use them against what it defines as "anti-social elements".
From the IRA's perspective, such killings are useful in showing the organisation's muscle and in demonstrating that in the battle against drugs it can deploy methods that the RUC cannot.
At the same time, however, the escalation in killings would almost certainly not have happened if the British government was closer to meeting the republican demand for calling early all-party talks.
Disillusion with the peace process has grown steadily in recent months in republican circles, where the view is now almost universal that the British government is not serious about allowing Sinn Fein fully into the political processes and of aiming for an all-inclusive settlement.
The killings appear to be a sign of this republican frustration, but they also strengthen the arguments of those who believe the republicans were themselves never serious about turning away from violence. Although attacks on soldiers and police have stopped, the six shootings will be taken as evidence that the IRA always intended to use force, or the threat of it, to achieve its ends.
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