The planned mortar attack is a reminder of the threat.
After a period of relative quiet, this was the dissidents raising their heads once more.
In recent times there had been concern that they would attempt a headline-grabbing attack in the period of the G8 summit or the World Police and Fire Games.
That didn't happen – maybe because it was too obvious, too much of a risk for organisations that are under constant surveillance to try to do something within such a specific calendar period or timeframe.
But they haven't gone away – this latest planned attack is confirmation of it.
"It's something that hasn't worked," a security source commented, with an emphasis on those two words "hasn't worked".
And in that short sentence he was describing a pattern – the flaws and weaknesses that are part of the dissident story.
Much planned activity is an open book; seen and heard in the watching and listening that is the stuff of covert intelligence operations and which leads to attacks being interrupted and arrests made.
The leaders and 'players' are known – their names on the tips of many tongues, and not just in policing and intelligence, but within their own communities.
There are few secrets. The dissident story is not a mystery.
Another trend is what doesn't work – the devices that don't function or detonate or fire or that have to be abandoned.
And it is into this general category that this latest planned attack fits.
Whatever was intended "hasn't worked".
In the description of these events there is always missing detail and so we are left trying to read between the lines.
The planned mortar attack was clearly the intended endpoint in this plot, but something else happened to try to lure police into that area and into the firing line.
This, too, is a familiar, often-used tactic – a bogus call or some incident created to prompt a police response, to bring them into the trap.
It has been the modus operandi of the dissident groups including in recent months, and it is why the policing approach has to be so cautious; why, to use a term, these situations are often left to "soak".
The longer the dissidents have to wait the more likely they are to abandon a bombing mission.
There is another question.
If so much fails, why then is the threat still assessed as 'severe'?
There is a simple answer.
There is no such thing as 100% intelligence or security. There are always blind spots – ways of getting in under the radar.
And we have seen the deadly consequences of those moments the dissidents would describe as their "successes".
This list of organisations – the dissident IRA coalition, Oglaigh an hEireann (ONH) and the Continuity IRA – have a bomb-making capacity and guns.
They won't always be seen and heard; won't always be interrupted, won't always fail.