Techniques of Systems Analysis looks at how its toy-model defense system will perform if the enemy happens to develop tactics outside its 1950s-era model — for example, an air-ground missile:
At this point the reader may cry foul. He probably feels that we have no right to introduce an extraneous tactic. After all, we promised to stick to a definite model. We did, but we want to show that it may be disastrous when the enemy doesn’t.
The air-ground missile is such that it can be launched from a point beyond our local defenses. The effect of this is that our local defenses no longer play a role. This can be serious. It means, in fact, that the money spent for local defenses has been thrown away. However, this new tactic is not entirely free to the enemy because his CEP (aiming error) goes up when he uses it.
The last question is what should we do? Well, a lot depends on the pattern of information that we think exists. Let us assume that the enemy knows everything that we are doing. In this case, he is practically certain to choose what is best for him. Our alternative must be to design a defense system which is indifferent between the two attacks so that we don’t care which he uses. This is the old problem of dividing a cake.