Quick Answer
Visit all three marked keycode stations, then enter the code displayed by your mission tracker at the armory keypad to open the armory in Operation Iron Citadel. The MW4 DMZ armory code objective takes place inside the Chang-san Air Base bunker, after you upgrade and collect the Airbase Access Card. Follow your current run's tracker rather than copying someone else's number.
How do you reach the Iron Citadel armory?
Find the Airbase Access Card, upgrade it at the marked server, and collect it before heading into the bunker. The armory doors are inside, so the card stage comes before the keycode hunt.
Operation Iron Citadel is a tier-two story mission at Chang-san Air Base. Its mission card carries a CRITICAL threat assessment and recommends a 3-Plate Armor Vest, a Medkit, and an Ammo Box. Take that equipment recommendation seriously before committing to the base: the bunker itself displays THREAT: EXTREME.
If you are still at the FOB, go to the helicopter pad, press DEPLOY, choose STORY MISSIONS under SELECT DEPLOYMENT, and select Operation Iron Citadel. The MW4 DMZ missions page covers the wider story-mission structure. For the base's place in the exclusion zone, keep the MW4 DMZ Hajin map handy.
Search the marked access-card locations
Follow the mission markers into Chang-san Air Base. Search the marked locations for the Airbase Access Card, using scan updates to narrow your search. Let those updates guide your movement instead of committing to a fixed card coordinate.
Finish the server upgrade
Carry the card to the marked server and start the upgrade. Keep the area clear until it finishes, then collect the upgraded card before leaving. Starting the upgrade is only part of this step; you still need to pick up the finished card.
Find the bunker armory doors
Enter the bunker and locate the armory doors. This brings you to the part of the operation where you recover the keycode parts and open the armory.
Where do you find the three armory keycode parts?
Visit all three keycode stations marked by the mission. Follow the objective markers for this stage inside the bunker, with your mission tracker as the reference for the armory code.
The useful distinction is between reaching the armory doors and completing the code objective. Finding the door gets you to the destination, but you still have the marked stations to visit before entering the code. Treat the stations as your immediate objective once you reach this stage.
- Check the active objective after reaching the bunker armory doors.
- Follow the mission markers to the keycode stations and visit all three.
- Read the code displayed by your mission tracker before using the armory keypad.
If your next stage does not appear after the access-card upgrade, check your current tracker and whether you collected the finished card. Do that before searching deeper into the bunker for code parts. It gives you a concrete earlier objective to check rather than sending you around looking for a different keypad.
What code do you enter at the armory keypad?
Enter the code shown by your own mission tracker after visiting the marked keycode stations. That is the number to use for your run when opening the armory.
Keep the tracker and keypad paired in your head: the stations are where you recover the parts, the tracker gives you the code to enter, and the armory keypad is where you use it. You do not need to substitute a number from another player's run for the one your objective displays.
Use your current run's code rather than copying a number from someone else's gameplay. Check your tracker at the keypad so you are working from the objective you actually have.
This is an operation objective tied to the bunker armory. If you are looking for an item used to open a different locked location, continue with MW4 DMZ keys for that separate search.
What do you do after opening the Iron Citadel armory?
Collect the armory manifest, then continue the sabotage objectives and exfil with the manifest. Opening the door is a milestone within Operation Iron Citadel; the operation continues beyond the keypad.
The remaining objective sequence is:
- Collect the armory manifest.
- Plant explosives in the armory.
- Plant explosives on three strike aircraft.
- Capture the SAM site.
- Exfil with the armory manifest.
The manifest matters at both ends of that sequence: you collect it in the armory and carry it out during exfil. Keep that final objective in mind while moving on to the aircraft and SAM site, rather than treating the door opening as the finish.
Completing Operation Iron Citadel awards LTV infil, a Supreme Leader Access Card, and 25,000 DMZ Cash. Once you have extracted with the manifest, return to MW4 DMZ missions to choose your next story objective.
FAQ
There is no fixed number. Visit all three marked keycode stations in the Chang-san Air Base bunker, then enter the code your own mission tracker shows at the armory keypad.
Inside the bunker at Chang-san Air Base. You first find the Airbase Access Card, upgrade it at the marked server and collect the finished card, then head into the bunker to the armory doors.
No. The fixed codes like 0024 and 8609 belong to the Stranded campaign mission. The Iron Citadel armory code is a DMZ story-mission objective, and the number comes from your own tracker.
Collect the armory manifest, plant explosives in the armory, plant explosives on three strike aircraft, capture the SAM site, then exfil with the manifest.