8-38. By definition, area security operations focus on the protected force, installation, route, or area. Protected forces range from echelon headquarters through artillery and echelon reserves to the sustaining base. Protected installations can also be part of the sustaining base, or they can constitute part of the area’s infrastructure. Areas to secure in the consolidation of gains may range from specific points (for example, bridges and defiles) and terrain features (including ridgelines and hills) to large civilian population centers and their adjacent areas. Population-centric area security missions are common across the range of military operations, but they are almost a requirement during irregular warfare. These population-centric area security operations typically combine aspects of the area defense and offensive tasks, like search and attack and cordon and search, to eliminate internal defense threats.