Adversarial Risk Analysis in support of defensive resource allocation for counterterrorism

Terrorism risk assessment is one of the biggest challenges that authorities must face to define the defensive resource allocation policy for a country. This article provides a brief review of two approaches that have been traditionally used for this purpose: Probabilistic Risk Assessment and Game Theory. Additionally, it introduces the Adversary Risk Analysis approach to the Brazilian context; an innovative methodology that aims to assess risks caused by intelligent opponents. Finally, an application of Adversarial Risk Analysis in a hypothetical situation is presented. The results show that Adversarial Risk Analysis can be useful to support decisions about defensive resource allocation in contexts such as sports mega events, a reality for many countries around the world.