We have recently introduced a framework for adversarial risk analysis (ARA), aimed at the analysis of decision making when there are intelligent opponents and uncertain outcomes. We present here how such a framework may help the owner of a cargo ship in managing risks from piracy in the coast of Somalia. The ship's owner will proactively decide on a defensive strategy to reduce piracy risks, ranging from different levels of deployed armed security to sailing through alternative much longer routes avoiding such area. The Pirates will respond to the defender's move by launching (or not) an attack with the intention of taking over the ship and asking for ramson. If the Pirates' operation is successful, the ship's owner will have to decide on: paying or not paying the ramson, or even sending armed forces to release the ship. We illustrate how a standard counterterrorism model like the sequential defend-attack-defend model can be used to formulate our supported decision maker's problem. We show the kind of solution proposed by our ARA methodology and computations. Emphasis will be put on explaining how we can model the Pirates thinking in order to anticipate their behaviour and how it would lead to a predictive probability distribution, from the defender's perspective, over what the Pirates may do. We also compare our solution to those obtained using an standard game theoretic approach.

Keywords: Adversarial risk analysis; Decision analysis; Strategic decision making