1. Enter the base and disarm security system
2. Enter high security compound and board train
3. Eliminate all resistance
Slide down the ladder and equip your M16. Run to the right, shoot the guy on the tower (A2), turn left onto the bridge, shoot the guy in the tower to your left. Shoot the guard patrolling across the end of the bridge before he presses the alarm, then run round the security cabin and hole up in the corner between the ramp and the platform. Watch map view to see when a patroling guard walks up the far side of the platform and take him out when he comes into view. Then watch map view fo the guard patrolling alongside the next platform and take him out when he turns away. Go up the ramp onto the platform slowly. As soon as you see the guards(use binoculars) wait until they are away from the alarm (at the far end right) then run down the platform and shoot them as you go. If they do start the alarm it gets alot harder. As you run down stay away from the left side of the platform as the sniper will see you. At the end of platform you see a ramp. Go onto it slowly and sideways looking up at the tower to your left. Shoot the sniper standing on it. Then run down to the truck and shoot the guy behind it. If you hear shouts take the machine gun and hit any guard coming from the tracks. Run back to the sniper gantry, climb and take Druganov. I dont know if you need to but I then shoot the three guards patrolling between the platform. Shoot the guards in the tower at the far side. Make sure to hit the guard patrolling the outside cleanly because if he gets alerted he will push an alarm which is on the right of the tower as you look at it. Go back to the truck and beyond it and over the bridge.Shoot the guy through the window, enter the building and be prepared to move fast. The alarm button is in the first room and if you dont get the guy in the first room fast he will sound it. One more in the next room (with the computer in it) one or two in the last room. The first guard may regenerate and follow you so look out. Once you've cleared the area, hack the computer, and leave through the door to your right - watch out for another guard as soon as you open the door. Wait for the train to get fairly close (now is a good time to use the medipack you started with), then follow the tracks and run alongside it, through the gates and up onto the platform. Enter the last car by picking the lock, kill the guy right in front of you, and run to Jach. Go easy with fire power in the car because Priboi is right behind the guard. If you are not quick you will soon be joined by other guards from the guardhouse at the far side of the tracks.
Note that the alarm must not be raised more than 30 seconds in this level. Do not shoot at the camera near the gate (objective 2 on the map) unless you have disarmed the security system (and then it's no use). The only place you can turn off the alarm if you dstroy the camera is in the office building (objective 1 on the map).Climb down from watchtower. The hill is very steep, you can easily break a leg or even die if you're not careful. Slant down the hill northwards (towards the two watchtower near the bridge leading to the compound). You will see two guards patrolling a ramp under a shelter. Do not fire at them. They will start the alarm, and then you'll have to restart the mission. Place yourself about 55-60 m. from the northernmost watchtower and use your binoculars and M16 to take out the guard. Do the same with the guard in the next watchtower. You'll have to stand further away from the second guard and perhaps be tempted of entering the bridge and shooting him from there. If you do, stand at sufficient distance (more than 50 m.) since if he sees you and fires back, one of the guards patrolling the ramp will hear it and start the alarm.
At some "tower" behind the ramp of the patrolling guards is a sniper. It is well spent bullets to shoot him from a distance as well. When he is down, take the bridge. Stop halfways over and look at your map. There's a guard patrolling in front of the bridge. He stops at a point just north of the bridge's end. When he turns around and stats walking towards the crates, run and shoot him in the back. He will try to go for the alarm when he is "alerted".
Go behind crates at eastren side of base.Move to shelter and blast away the two guards before they hit the alarm button. If one of them do, quickly reset the alarm (push the button), turn around and blast a grenade into the machine gun post. Then enter "tower" where the sniper was to obtain Dragunov. Some guards patrolling the train yard might spot you. You can either shoot back or you can run towards the bridge at the eastern part of the compound.
If the alarm wasn't turned on the heavy machine gun guy will be standing behind the truck near the gun post. He will run for the post rather than shooting at you, so he's an easy target. Then enter the bridge and go to where the fence ends (at the northern side). From there you can snipe a guard behind a window (see screenshot).
Continue down and into the building. There will be two guards left in the building. The first you kill (who is trying to get to the alarm button) will respawn, so you will meet him when you exit the building as well. In the room where the guard you shot from the bridge was standing is a computer. The screen is dark blue (all other computers you can hack in the game have light blue screens). Hack the computer and exit the building. If you're fast now you will be able to blast away guards with your M16 grenade. Run towards the gate.When you can see the guard in the tower, snipe him. Continue to the gate.There are 10 M16 gernades in basement of ammo building.If you want to pick them go in it.It is not important for completing this mission .There are 2 guards in it.But it is risky.If you not want to pick them move towards the gate where the camra is.Pick the lock and enter through the gate.When train is running do not come near it or you will dead.
Guards will emerge from barracks at the northwest of the compound (see screenshot). You can blast them away with a M16 grenade or you can wait by the gate (don't run ahead, they will spot you and do serious damage) and snipe them when they are on place on the platforms beside the train that just arrived. The guards will respawn and come running again from the barracks, so run to the train when you have killed them the first time.
Go to the front coach (the one furthest away). Pick the lock and enter. There is a guard waiting in the coach. Don't use unecessary force when you're killing him, since Priboi is standing behind the crates (behind the guard). When the guard is dead, walk around the crates to Priboi.
In Cut-scene train goes into tunnel.