A bilevel fixed charge location model for facilities under imminent attack

► We investigate a bilevel fixed charge facility location problem for a system planner (the defender) who has to provide public service to customers by opening facilities at candidate locations. ► Facilities can be opened either in the protected or unprotected mode. Protection immunizes against an attacker who is capable of destroying at most r unprotected facilities in the worst-case scenario. Partial protection or interdiction is not possible. ► The problem is formulated as a static Stackelberg game between the defender (leader) and the attacker (follower). ► Two solution methods are proposed. The first is a tabu search heuristic where a hash function calculates and records the hash values of all visited solutions for the purpose of avoiding cycling. The second is a sequential method in which the location and protection decisions are separated. ► The produced solutions are validated by means of an exhaustive search algorithm.