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The subject of this article appeared in Call of Duty: Modern Warfare 3.

"Stop the Russian submarine from having a nuclear meltdown."
— Level Description

Over Reactor is a Special Ops Mission Mode mission in Call of Duty: Modern Warfare 3. It requires the player to infiltrate a submarine in danger of having a nuclear reactor meltdown and then escape in a helicopter.


The player begins by landing outside of the submarine's exterior via helicopter. The player is immediately assaulted by two soldiers. After dispatching them, the player must defuse a thermite charge and enter the submarine. After traversing several maze-like floors littered with enemies, the player must stabilize the reactor and proceed to escape. After traveling up a ladder and back onto the submarine's exterior, the player will be assaulted by a large force of soldiers rappelling in from helicopters with the aide of smoke grenades. After dispatching the soldiers, the player must hold off on the submarine until a helicopter arrives to evacuate the player, completing the mission. Thermal vision is available.


The Russians have rigged a sub in New York Harbor for a nuclear meltdown, and the player is dropped onboard to avert the catastrophe. Two soldiers emerge from the smokescreen ahead. Try to take them down before they come out. Thermal vision is useful for this area.

Disarm the thermite attached to the hatch and then climb in. A five-minute timer starts counting down to the point of meltdown. The player must reach the reactor before the timer hits zero.

Turn the thermal vision on as you fight your way through the first compartment. This makes the enemies easier to spot.

With two players, one should go up and the other should go down. This makes reviving more difficult, since the player have to run up or down the stairs to reach their partner, but it allows the player to watch each other's back easily.

Meet up below and then split up, one left and the other right. Push into the reactor room and have one player use the valve to shut down the reactor. The other player should keep watch out in the hallway. Enemies will come out during the turning of the valve.

Continue up the steps and through the bunkroom. Climb up the ladder to exit the sub.

Use the crates for cover as more Russians are dropped on top of the submarine. Once the player has eliminated that group, split up and move toward the extraction point.

The enemy troops put up a smokescreen, so use the thermal goggles to see them coming. Fight the way to the helicopter and the mission will be completed.

Weapon Loadout

Starting Loadout
Found in level



  • After traveling up the ladder onto the submarine's exterior at the end of the level, it is possible to climb down again for cover.
  • When the player tries to go to the hatch where the player and Sandman entered, it will not allow the player go there and it will say "Turn back and continue the Mission!".
  • If the player goes back to the front most hatch after the player successfully shut down the reactor, the player is unable to climb back there and must go to the hatch where the player and Sandman entered instead.