Operation Iron Citadel is the hardest MW4 DMZ story mission we have played. It sends you into Chang-san Air Base, the base run by Lieutenant Bale, to find an access card, break into the armory in the bunker, steal the ordnance manifest, blow up three strike aircraft and capture a SAM site out in the open. This walkthrough covers every step, the random keycode, the fights that end most runs and what the mission pays. We played it solo first and then finished it with a full squad.
- Iron Citadel takes place at Chang-san Air Base, a Critical threat mission. The base and the bunker are rated Extreme once you are inside.
- The mission has ten steps: from finding an access card to exfil with the armory manifest.
- The six-digit armory keycode is random every match. Read all three notes in the bunker.
- Colossus, the minigun Commander, can show up in the bunker. Shoot him only between his bursts.
- The SAM site at the end is the hardest part: open ground, a swarm of enemies and other squads.
- Rewards: a Bunker Access card, an LTV and $25,000, plus 12,500 XP.
Operation Iron Citadel at a Glance
| Detail | What the game shows |
|---|---|
| Location | Chang-san Air Base, Hajin |
| Threat assessment | CRITICAL |
| Recommended equipment | 3-Plate Armor Vest, Medkit, Ammo Box |
| Main objectives | Infiltrate the Base, Recon Armory Ordnance, Disrupt the Operation |
| Rewards listed | Bunker Access card x1, LTV, $25,000 |
The base belongs to Lieutenant Bale, and your main job is to recover his ordnance manifest. Lieutenant Ko stays on comms with you throughout the mission.
Click to enlarge Iron Citadel on the Select a Mission screen. 
How to Start Operation Iron Citadel
Open Select Deployment, choose Story Missions and pick Operation Iron Citadel. It sits one row up on the mission tree, above the three missions that close a DMZ Orders chapter, and stays locked until you have finished those three. Once it opens, you deploy in the North Korean Wilderness, a few hundred meters from the base.
Operation Iron Citadel Walkthrough
1. Approach the Air Base
Head for Chang-san Air Base. On the way in we ran into the Commander Colossus in the North Korean Wilderness, so stay alert before you even reach the fence.
2. Search for an Access Card
Four search zones show up on the tac map across the base. Loot the containers inside them. Every container you open scans for the card, so keep searching zone by zone until the game tells you the keycard has been found.
3. Pick Up the Access Card
The card is an Epic key called the Air Base Access Card. Ours lay on an office desk. Make sure you have backpack space, because a full backpack blocks the pickup.
Click to enlarge The four access card search zones on the base. 
Click to enlarge The Air Base Access Card on an office desk. 
4. Upgrade the Access Card
Take the card to Admin Complex No. 2. The keycard door there needs the Air Base Access Card. Inside, use the terminal to upgrade it and take the single-use Armory Card it gives you.
5. Find the Armory Doors
The upgrade sets off the base alarm, and every soldier on the base goes on high alert. The armory is in the Chang-san Air Base Bunker, which you enter through the Entrance Garage. Expect heavy resistance from here on, and possibly Colossus in the bunker.
Click to enlarge The upgrade terminal in Admin Complex No. 2. 
Click to enlarge The base alarm goes off after the upgrade. 
6. Find the Armory Keycode
The armory door needs a six-digit code. Three notes in the bunker each hold two of the digits. In our first run they were in the medical wing, the administration area and the Control Room. The code is random every match: our first run was 294324, and our second run showed different digits altogether.
Click to enlarge One of the three keycode notes. 
Click to enlarge Entering the code at the armory keypad. 
7. Explore the Armory
Inside, find the Armory Manifest. It shows that the explosives are meant for a set of specially equipped jets parked in the hangar and out on the tarmac. Those jets are your next target.
8. Plant Explosives on the Strike Aircraft
Three jets are marked on the base. Plant explosives on all three. They are spread out, so move as a squad and clear each one before you plant.
Click to enlarge The Armory Manifest points you to the jets. 
Click to enlarge All three strike aircraft rigged. 
9. Capture the SAM Site
Next the mission sends you to a SAM site on the base. Capture it at the laptop on the launcher, which also pays 150 XP.
10. Exfil the Armory Manifest
The last objective is to get out with the manifest. In our full run our operator went down right at the end and went Missing in Action, but the mission still counted as completed and paid 12,500 XP.
Click to enlarge The SAM site captured. 
Click to enlarge Last step: exfil the Armory Manifest. 
Where Squads Get Stuck
Iron Citadel can be a very hard mission, depending on your loadout and your teammates. Our first attempt was solo and it went badly. We survived until the SAM site, and that part is the hardest. You are out in the open, the base is swarming with enemies, and other squads on the map can join the fight too.
The other big threat is Colossus, the Commander with the minigun that many players call a Juggernaut. We met him in the bunker. If he shows up after you open the armory, take him out right away so you do not have to worry about him for the rest of the mission. He fires in bursts: a few seconds of shooting, a few seconds of nothing. Only attack him when he stops, or that minigun will light you up. Taking him down also counts for the Boss Board, where Commanders pay $50,000.
Click to enlarge Colossus showed up in the bunker garage. 
Rewards and Payout
Iron Citadel rewards a Bunker Access card, an LTV and $25,000. The LTV is the best one. It lets you spawn in with the heavily armored LTV, an infil that otherwise costs 25,000 DMZ Cash every time you buy it. Finishing the mission is also worth 12,500 XP.
Loadout and Squad Tips
- Bring a strong weapon. This is not a mission for a starter gun.
- Wear a 2-Plate or 3-Plate Armor Vest, with 3 plates recommended.
- Pack plenty of Armor Boxes and Ammo Boxes, plus a Medkit and a Self-Revive Kit if you have one.
- Do not rush it. Build up a good operator first, with solid gear, a strong weapon and a good set of traits, then go in with two good teammates.
If you are new to the map, our MW4 DMZ Hajin map guide shows where Chang-san Air Base sits. The other story missions we have covered are Operation Critical Extraction, Operation Silent Ledger and Operation Shopping Hacks. The other hard one is Operation Grid Assault, the story ends with Operation Fallen Ember, and our DMZ Orders guide lists every order page.
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Frequently Asked Questions
How do you start Operation Iron Citadel in MW4 DMZ?
Open Select Deployment, choose Story Missions and pick Operation Iron Citadel at Chang-san Air Base. It unlocks once you have finished Operation Critical Extraction, Operation Silent Ledger and Operation Shopping Hacks. It is a Critical threat mission, and the game recommends a 3-Plate Armor Vest, a Medkit and an Ammo Box.
What is the armory keycode in Operation Iron Citadel?
It changes every match. The six-digit code is split over three notes in the Chang-san Air Base Bunker, two digits per note. Our first run used 294324, and our second run showed completely different digits, so read the notes every time.
What are the Operation Iron Citadel rewards?
Iron Citadel rewards a Bunker Access card, an LTV and $25,000. The LTV reward lets you spawn in with the armored LTV, an infil that normally costs 25,000 DMZ Cash. Finishing the mission also paid 12,500 XP on the after-action report.
Where is the SAM site in Operation Iron Citadel?
On the Chang-san Air Base itself. After you plant explosives on the three strike aircraft, the mission sends you to capture a SAM site on the base, out in the open while the base is swarming with enemies. Capturing it completes the step and pays 150 XP.
Can you do Operation Iron Citadel solo?
You can try, but it is the hardest story mission we have played. Our solo attempt made it to the SAM site before going down. With two good teammates, strong gear and plenty of armor and ammo boxes it is very doable.
