The contrast is with the loyalist paramilitary groups, which have often frankly admitted their intention of inflicting civilian fatalities, so long as the victims were Catholic.
Their republican counterparts have generally been concerned to project themselves as disciplined military outfits rather than indiscriminate "mad dog" terrorists.
They have thus, with some exceptions, tended to issue statements in the wake of bombings which cause civilian casualties saying this was not their intention.
The Real IRA statement claiming ample warning was given is therefore very much in line with tradition, for in such cases the republican tactic is to attempt to shift the blame on to the authorities. The intention is to argue that the responsibility for casualties lies with the authorities rather than the bombers themselves.
While such claims may not wash with much of the outside world, they have a certain use in republican areas, where many grassroots supporters are eager to blame the authorities rather than republicans for civilian casualties.
In many republican bars and haunts it is fiercely argued that the authorities have even deliberately ignored warnings so as to cause casualties and thus discredit republican groups. Few outside the fanatical fringes are prepared to countenance such allegations.
In the case of Omagh the debate is continuing about whether the intention was to cause commercial destruction, as has been the case in previous Real IRA attacks, or whether the aim was to take life on a large scale.
If the authorities were convinced that slaughter was the intention they would presumably have introduced stringent new parking restrictions as a matter of great urgency, but they have not do so.
Republican organisations which have caused large-scale civilian fatalities have tended to pay dearly for doing so in terms of public support and sympathy in republican circles.
In this case that effect has been magnified by the fact that so many of those killed were women and children, and by the fact that many of the dead were Catholic. In such circumstances, and in the wake of the Good Friday agreement which won the support of more than 90 per cent of republicans, it appeared last night that even republican grassroots supporters were continuing to blame the Real IRA for the deaths, whether the killings were deliberate or due to a foul-up.
Yesterday's statement therefore contained nothing of real surprise to the security forces on both sides of the border.
The British and Irish governments and police forces have in fact been formulating a security response to the attack which is based on the premise that the group was to blame.
The Real IRA is said to consist of fewer than 100 activists, most of whom are based on the southern side of the border. Its members are thought to be concentrated in and around the border town of Dundalk in Co Louth.