NPCs | Campaign - introduction & Command Center JA: Crossfire Guide

Traders: after liberating the land, you can also buy and sell items via NPC (dollar icon over the NPC). Every merchant has limited amount of money: if you get all of them, you have to look for another merchant, or buy something from him. Part of merchants start trading with you after completing some secondary mission.

Secondary missions: after liberating the particular region, NPCs with the exclamation mark will give you additional missions. Most of them are very profitable or allow you to recruit additional mercenary, so you should complete them. Their detailed description you can find in the Secondary Missions chapter.