The Barrier is a strategic outpost in the Army Warehouses that acts as the zone's main line of defense against the Monolith. The outpost is built at the mouth of the canyon that leads into the Red Forest and is the most direct route to Chernobyl NPP. It acts as a funnel for constantly attacking Monolith and mutants. It is also the closest possible place stalkers can be stationed to CNPP without being affected by the Brain Scorcher.
It is similar to the Duty checkpoint but this time, Loners (in Clear Sky) or Freedom (in Shadow of Chernobyl) guard this area and the Monolith are the major threats, though some hordes of mutants can also appear.
In Clear Sky, the Barrier is protected by Loners who by other stalkers are said to be some of the most hardened, skillful stalkers in The Zone. These stalkers probably see more action than anyone else in the Zone, and are constantly being bombarded by the Monolith and mutant attacks coming out of the Red Forest. The player can help assist the stalkers here at the barrier against the Monolith for a cash reward back at their base in the Cordon. The road beyond the barrier that leads to the Red Forest is inaccessible for Scar because the Brain Scorcher is still active. If the player tries to take this road, he will take heavy psychic damage, up to the point where he simply dies.
Shadow of Chernobyl
In Shadow of Chernobyl, the Barrier is protected by Freedom. Like in Clear Sky, the Monolith constantly attack the barrier to try and get through into the Zone because it is simply the most direct route from Chernobyl NPP. The Freedom members stationed here have one goal, to keep anything that comes out of that canyon from swarming into the rest of the Zone. When the player receives his psy protection helmet, he is able to make it through the canyon into the Red Forest. The player fights his way through numerous Monolith troops stationed all throughout the road towards the Brain Scorcher. When the player finally deactivates the Scorcher, he emerges from the lab and finds that stalkers from all factions are flooding into the forest towards the CNPP. The first stalkers besides Strelok and the Monolith to step foot in this side of the Red Forest are the Freedom members that were stationed at the barrier, and the player can fight his way into Pripyat alongside them, if Duty doesn't kill them off as they attempt to reach CNPP. If the men defending the barrier are beaten, the Monolith fanatics will pour fourth in a killing rampage, maiming and burning all in their path until they deem their work done; at which point they will slink back to their staging point in the Red Forest.
- If the Marked One's reputation with Freedom is damaged, he will have to fight them alongside with the Monolith and several mutants. In fact, the task "Protect the Border" will automatically fail everytime he enters the Army Warehouses.