The available options are:
Additional supplies to use during the mission.
The additional goal is related to the security systems and lowers the difficulty during disarming the other systems.
Lowering the enemies' numbers.
This is definitely the most interesting option, which will make the mission much easier.
There will be a briefing with Sean Darcy before the mission starts.
In the other case, it can be more difficult.
I’d suggest firstly going down the ladders.
Keep an eye on an active machine gun in the western part of the camp.
Look out, as there’s a guard inside the adjoining building.
Use the stairs and go upstairs.
Find the generator (M3, 7) and switch it off.
Now you should eliminate the two others enemies, which shouldn’t be too problematic.
Now you might localize the door leading underground (M3, 8).
After securing the area, head towards the passage leading to the next room (M3, 10).
Ultimately you should reach a gate leading to the cells (M3, 12).
Now you’re able to head towards the southern door (M3, 13).
Keep focused, as you will reach rooms patrolled by the enemy soon.
Just like before, a quiet elimination is possible, but quite hard.
You will find it in one of the badly lit rooms (M3, 14).
TRANSFERRING THE DATA:
Approach the main computer (M3, 15) once you decide you’re ready.
you’re free to break into the system by solving a mini-game or using an EMP charge.
RETURN TO THE SURFACE:
Quickly hide by one of the three passages leading into this room.
Enemies have appeared in the area and you have to deal with them.
Instead just throw a grenade (screen) and finish off the survivors with conventional weapons.
Most of them are busy shooting at the helicopter, so eliminating them will be quite easy.
Afterwards eliminate the enemies with rocket launchers.
Leave the further targets, including the enemies by the deactivated generator for the end.

EVACUATION:
You should hide right after eliminating the last enemy, as a new wave will appear shortly.
Use the switch and deal with the last two enemies.
Getting to the helicopter (M3, 18) will end the mission.
After returning to the hideout, there will be a briefing with Sean Darcy.
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