Optimal Terminal Defense Tactics When Several Sequential Engagements are Possible

In this paper we treat a situation in which a terminal defense wishes to minimize the expected fraction of a target destroyed. Attacking reentry vehicles (RVs) arrive simultaneously, and therefore the defense knows the attack size. Several sequential engagements of the RVs by defensive interceptors are possible, and the defense has the capability to shoot-look-shoot between these engagements. Using techniques of stochastic dominance and stochastic dynamic programming, we determine optimal defensive tactics as functions of the numbers of RVs, interceptors, and engagements remaining; the various single-shot kill probabilities are parameters. We examine extensions of the basic model that determine both the expected number of interceptors remaining after the attack and the minimum number of interceptors needed to provide a desired level of protection of the target.