In a military context, the process of planning operations involves the assessment of the situation, the generation of Courses of Action (COAs), and their evaluation according to significant points of view, in order to select the COA that represents the best possible compromise. To support this process, an advisor tool has been developed to assist a military Operation Centre staff in managing events and their related COAs, as well as prioritizing these COAs according to different evaluation criteria by means of a Multicriterion Decision Aid procedure. This paper describes an automated approach for explaining the ranking proposed by this decision support system.