George Hamilton, just appointed to the top policing post here, spent part of yesterday talking about the Londonderry bomb.
Of course, he already knew all about the reality of the dissident threat, but he also knows that the continuance of that threat is slowing down the introduction of new policing.
This time a hotel was the bombers' target. Three years ago, a device in a holdall was thrown into a branch of Santander bank in the same city and exploded inside an hour.
The warning at the Everglades Hotel on Thursday night was 40 minutes – just enough time to evacuate staff and guests, but not long enough for Army experts to get in to dismantle or disarm the device.
These are the thin margins the dissidents play with. This time, the bomb exploded as intended and the group that now claims the name of the IRA got another headline – targeting a hotel that hosted a PSNI recruitment event, and due to hold another next week.
There's a tug-of-war between new policing and the old threats. And change has to be measured against those threats.
George Hamilton will know that. The dissident IRA recently threatened more attacks against police, so part of the thinking about change has to be considered within that wider context – a bomb in a hotel, a bomb at a bank or bombs under officers' cars.
Reform is not happening in a completely peaceful environment. Sir Hugh Orde had to measure change against threat, so did Matt Baggott and, in several weeks' time when George Hamilton takes charge, the same threats and challenges will be waiting for him.
Not all the 'wars' are over. And not all the answers will come from security and policing and intelligence.
If George Hamilton is to deliver something that will have the look of brand new policing, then people and politics will have their parts to play also.