What are you doing here?
This is a secret room in the Recoil Mission of Condition Zero Deleted Scenes. You can find it after planting a Remote Controlled Bomb in the bombed out building. It's the room where a sniper was waiting for the player outside of the building: there are two pipes near the sniper's nest, find them and use them as a ladder. You will enter in the room where you can find supplies and a Machete Terrorist.