Seveso III Directive (2012/18/EU) requires operators to demonstrate that they have identified major accident hazards and scenarios, and that they have implemented adequate actions to prevent such accidents. Safety reports issued under the Seveso Directive specifically address accident scenarios caused by technical or human failures. Scenarios caused by intentional acts are usually not considered, even if they have a wide potential to harm the workers and the exposed population in the vicinity of Seveso sites. The present contribution focuses on the characterization of physical security-related scenarios in the framework of safety and security management of Seveso sites, identified taking advantages of the potential synergies between safety and security studies. The role of physical security barriers is explored. Finally, the use of protection distances from critical and vulnerable units is presented to support the selection of the barriers.