So much of the intelligence battle with the dissidents is a mind-game: it is about playing inside their heads; not so much making them think, more about making them worry.
And this is the real importance and worth of information. It is not just about stopping the latest planned attack in Derry, but making the dissidents think and worry about how it was stopped; making them doubt and question those they thought they could trust.
They will want to know if they have been compromised from the inside – from within their own ranks.
And they will be asking: 'Who knew the plan? And who's talking?'
That means going through this from A to Z – where it started and how it ended. And, for the dissidents, the answer to that question is: once more in failure.
There is much for them to consider:
Was it compromised in their so-called 'engineering department' by those constructing the mortar bombs and the launching structure?
Who were the thinkers behind the plot, those involved in the planning, targeting and giving the orders? Can they be trusted? Can anyone be trusted?
What about the work that had to be done on the van, cutting out the roof and fitting the launching tubes and bombs? Did anything go wrong there?
Inside their heads, they will re-run every detail, looking for the weakness that meant these mortar bombs were never going to get to their target – were never going to get to the point of being fired at a police base.
But what if the information didn't come from the inside? This opens up other possibilities; that they have been seen, or heard, by those watching and listening from inside that world of intelligence.
So the dissidents will think about where they are most vulnerable to the monitoring of MI5.
These are the mind-games that cause doubt; playing inside their heads to the point where they have to think and think again before they move. It won't stop the dissidents, but it will slow them down. And it's not just about this latest setback, but about something that now fits into a pattern.
You can follow it from the murder of prison officer David Black at the beginning of November.
In Belfast, a bomb placed under a car being driven by a soldier fell from the vehicle. In the same period, a Semtex device being moved in Derry was seized and arrests made.
Then, just days after a senior intelligence source told this newspaper that dissidents were planning multiple-casualty attacks, a police officer discovered a bomb under his car.
He was about to take his family for Sunday lunch. And, in this, we see the fine lines between life and death, between what the dissidents would term success and failure.
The pattern has continued in recent weeks; a botched attack on a police officer at his home in Omagh, rocket-launchers found in Co Tipperary and then in west Belfast and now this latest security operation stopping a plan to launch mortar bombs at a police base.
For the dissidents, it is happening far too often to be dismissed as bad luck. And they will know that this is down to good information, too good in their terms.
A security source described it as a run of "good results". But the dissidents will see it as something much more than that; results achieved not by chance, but because of knowledge – maybe inside knowledge.
And all the time they will be asking: 'who can we trust?' The more they have to think, the more they are slowed down in this mind-game that makes them worry whether it is safe to move.
When the new dissident IRA coalition was formed there was a 'winnowing process', trying to eliminate weakness, weeding out those they couldn't trust. And still they can't move without being compromised.
"This particular grouping hasn't had much success since its formation," one source commented. But that source also knows that, in these battles, the pendulum swings; that the security and intelligence results won't always be good and that, at some point, the dissidents will get under the radar.
An example of this was the murder of David Black, when the planning wasn't seen, or heard. But this has been the exception, rather than the rule.
The dissident leadership is known; those who are the thinkers and the planners. And the more they try to do, the greater the risk for those they are sending out on these so-called 'operations'.
An intelligence source, speaking to this newspaper, described the latest security operation as "a hard stop" – meaning the police knew exactly who and what they were looking for.
That intelligence world has known from previous finds that the dissidents were trying to develop mortar technology.
But this is the closest the new IRA coalition has come to firing it – except they didn't come close at all.
MI5 and the police knew what was coming and knew what they were stopping. What the dissidents don't know is how they knew. That doubt and confusion is good news for those involved in the intelligence war.