The Perimeter as a System
Treat the site as a set of concentric rings, not a wall. Each ring buys time; time buys a response. The fence does not stop an intruder, it delays one long enough for detection, assessment, and interception to close the loop. Design every layer to do one job well and to hand the intruder to the next layer weaker than before. A perimeter that only deters is a perimeter that has already failed, because a determined adversary is not deterred, only delayed. Measure your perimeter in seconds of delay against minutes of response, and you will know exactly where it breaks.
Knowledge check
Why is physical delay, rather than prevention, the correct design objective for a site perimeter?
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No barrier is truly impenetrable, so the perimeter's real job is to impose enough delay that detection and an armed or trained response can intercept the intruder before they reach the asset. Delay is measurable and stacks across layers; prevention is an illusion against a determined adversary.