It is time to leave some musty caves and take a gust of fresh Siberian air in a bigger location. You start by zipping down the line into the valley. Approach the extended line and press the A button. Another way to do this is to leap towards the line and Lara will automatically grab on to it to zip down.
After you pass by the dead soldiers, you will run into his companions. Get the first one from behind and choke him while he is still talking on the radio. Thanks to this, you obtain an achievement - One-Sided Conversation.
Then, hide behind the oil drums and pick up one of the bottles around. Listen to what the soldiers are talking about and throw the bottle towards the spot shown in the above screenshot. One of the opponents goes there to find out about the noise and turns away from the other soldier. Use the bow to shoot the soldier who is still standing still. Then, leave your cover to get clothes, approach the other soldier to the left of the railway car, and choke him.