You will have to go back to your hideout and use the laptop to begin your next mission. Use the narrow passage, marked on your map, to reach the mountain. When you reach the place presented in the screenshot, use the scout mode to find out where you can climb.
Reach your destination, crouch behind the pillar and use your drone to scan the area. Your task is to eavesdrop on an important conversation and interrogate one of the conversationalists.
Stick to the right side of the rocks and reach the place presented in the picture. You will have a clear view of the entire area and you will be able to get to the ruins easily. To eavesdrop on the conversation, hide behind the closest pillar on your right.
Once the conversation is over, the separatists will split up, and your target will stand on a small hill (he will be on the phone). As soon as he finishes the call, sneak up to him and interrogate him. You can leave the area and complete the mission, or secure another hostile outpost. One of the hostile soldiers is a Most Wanted criminal- Lt. Boris Druganin.
Unlocked reward that can be purchased for completing the mission:
- TMRP6 AV Mine - anti-personnel mine
- Wagram 21 Silencer - Silencer
- Wagram 21 Laser sight - Laser sight
- Wagram 21 Flashlight - Flashlight