hmm
My problem is the idea of a successful attack being a failure. The demand for perfect security ignores the complexity of perfect security and the absolute demand to remove freedom. People are demanding security services do better, security services are stepping beyond what would have been considered unreasonable and then people complain (rightly) of over-surveillance.
There are an unknown number of attacks being plotted against various people/locations/groups at any time and a limited number of security people to do the necessary work against threats of varying levels and complexity. If we count as a failure the lone unhinged nutter or the lucky complex attack succeeding then we are demanding a police state of heavy regulation and restriction. However a police state of heavy regulation and restriction is terrorising in itself.
I think both the demands on the security services and the security services demands have gone too far. Countries are sacrificing freedom for the belief of more security.