Controlling territory
The world is divided into regions, which are based on various points of interest and represent faction control over specific territory. Any given point in the world belongs to some region. Regions are dynamic and their borders can move - for example, when a new FOB is constructed, or an enemy outpost is neutralized.
The faction that controls a region will deploy patrols and set up checkpoints over its area. When neighbouring regions belong to opposing factions, these regions are considered border regions. Their shared border becomes a frontline, and will be marked on the map with a stripe pattern.
Military presence is stronger in border regions, regardless of the threat level. Additionally, spontaneous skirmishes may escalate in these regions due to close presence of opposing forces.