Optimizing counter-terror operations: Should one fight fire with “fire” or “water

This paper deals dynamically with the question of how recruitment to terror organizations is influenced by counter-terror operations. This is done within a optimal control model, where the key state is the (relative) number of terrorists and the key controls are two types of counter-terror tactics, one (“water”) that does not one (“fire”) that does provoke re-cruitment of new terrorists. The model is nonlinear and does not admit analytical solutions, but an efficient numerical implementation of Pontrya-gin’s Minimum Principle allows for solution with base case parameters and considerable sensitivity analysis. Generally this model yields two different steady states, one where the terror-organization is nearly eradicated and one with a high number of terrorists. Whereas water strategies are used at almost any time, it can be optimal not to use fire strategies if the number of terrorists is below a certain threshold.