Trying to get the Destroyer of Worlds achievement? Recently watched Oppenheimer? Trying to defeat a major nation after 1945? Here's the guide for you.

Nuclear weapons in HOI4 are one of the most powerful tools you can use, but it isn't immediately obvious on how to use them well or at all. There are 3 stages: Research, Construction, and Deployment.

There are 3 things you need to research in order to make and use nukes. Each takes 500 days at 0% research bonus. This is the longest research tier in the game, so be sure you have the time and IC to actually make it worthwhile.


First: Atomic Research. Doesn't really do anything but provide a 4% research bonus. Also part of the trigger for Race for the Bomb.




Second: Nuclear Reactor

This lets you actually build Nuclear Reactors. You'll want to get this one done a little early so you have the time to build up reactors before you research nuclear bombs.



Third: Nuclear Bombs

This allows your reactors to start actually making bombs. Until you unlock this research your reactors will do nothing except take up a building slot.


Fourth: You also need a strategic bomber in range, so you should certainly research this and build your own, but it's technically possible to get them without the research.

Once you've finished all three tiers of research, you can actually start producing bombs. Nuclear reactors produce nukes at a rate of one bomb per year per reactor. Thankfully they're magic and don't require you to actually mine uranium or plutonium, so you can build them as any country so long as you have the research and building slots.


At a rate of one bomb a year per reactor, you're going to want to build a lot of reactors. You can only build one reactor per state, and each one costs an eye watering 30,000 IC. That's roughly three times the cost of a civilian factory or twice the cost of a synthetic refinery. I'd highly recommend starting on high infrastructure states first.

As stated above, you can start building reactors once you've finished the 2nd tier of research, but they don't do anything until you finish the third tier. Consider your research bonuses, building slots, future land expansions, and so on when deciding your build order.

Actually using the nuke also requires a few hoops to jump through. You need to:

-Actually have a nuke (duh)
-Be at war with the place you're bombing
-Have 75% air superiority in the air zone you're bombing in
-Have a strategic bomber in range of the drop zone (the wing can be on a mission elsewhere, just needs to be within bombing range)
-Also you can't be currently dropping a nuke there


These can be a little bit tricky if you're not aware. The hardest part will be getting the 75% air superiority as late game AI loves to pump out fighters and clog the sky. Be sure to upgrade your fighters, upgrade the airports nearby, ensuring a proper supply line to the area, and/or just choosing an air zone that isn't contested, shifting a large number of wings to the area, then dropping the nuke before the AI can react.

Once all the conditions are met, when you click on a land tile in the bottom left corner a window will pop up and the nuclear icon will switch from grayed out to colored in. Click it to drop the nuke and a bar will quickly fill up (12 hours in-game) as the bomb is dropped. Then sit back and watch the fireworks.



There are special events which pop-up when the first nuke drops or if the nuke hits a special city. Those cities include the capitals of starting majors, Hiroshima and Nagasaki, and Copenhagen and Stockholm.

HOI4 nukes are often conflated with real life hydrogen bombs and ICBMs which came later. Early nukes are much weaker than the world-ending stockpiles built up over the following decades. Mechanics wise, nukes in-game don't wipe cities off the map, cause any civilian casualties, and don't even cause any permanent damage. However, they are still extremely powerful if used correctly and can easily break endgame stalemates when the AI is stacking an entire army on every tile.

Nukes will damage all the buildings on the specific tile, damage some of buildings in the whole states (think fort vs factory), damage roughly half the org and strength of all the units on the tile (important), will destroy any planes in a nuked airport (IMPORTANT!), and also deal some damage to the enemy's war support.

There's also a special case for Japan where if you take Okinawa and Iwo Jima, destroy their navy (down to 40 ships) and drop two nukes they can surrender instantly. Very nice for avoiding a late game naval invasion into a low supply mountain country.

In other words, nukes are tactically and strategically powerful. Tactically they let you push into heavily defended areas and do otherwise impossible tasks (like landing a tricky naval invasion.)
Strategically they're also powerful, as you can very quickly get the enemy nation into a death spiral of dropping nukes on their key industries, reducing their war support and their ability to make material to stop you.

One of the most underused abilities of nukes is its power to instantly delete airfields of planes.
This is the best way to fight against an enemy nation that has spent the past 20 years doing nothing but stacking fighters. Instead of shooting down a few fighters a day, you can instantly delete 2,000 and damage the airfield, reducing their coverage which makes it even easier to nuke the rest of their airfields. Repeat this process until they can't cover their air zones over the frontline where you can spam CAS and actually push.

It's also useful to drop them on ports and supply hubs, denying the enemy the ability to actually supply their troops. The AI will also garrison these tiles meaning that you'll also do some damage to their manpower and equipment stockpiles.

Remember that there is a 12 hour delay between you clicking the button and the nuke dropping, so if you're attacking a tile and you take it before the nuke drops, you'll drop it on your own troops! Use caution on these kinds of attacks.


Another possible tactic is to simply deplete the enemy's manpower by exploiting the AI's inability to merge divisions. Find the tile(s) with the most enemy divisions on it. Drop a nuke, cutting them roughly in half. Wait for the divisions to refill, then repeat. The AI will automatically take men from its manpower pool to replenish the nuked divisions, meaning you can quickly burn through their manpower (and equipment, but odds are that'll be in better reserve.) Do this enough times and eventually they'll run out of manpower and hopefully should be on low enough war support that they can't raise the conscription law any further. Once they can't refill their divisions, you can push with impunity.

The amount of war support lost is based on how developed the area is (infrastructure) and the amount of VP, so if you want to do the most damage to their war support, you need to actually stop strategic bombing so they can repair their infrastructure in their high-VP areas.

In short, nuke airports, ports, supply hubs, areas with high levels of development, and tiles with lots of enemy troops. If you need more nukes and are limited by the one per zone, take a look at areas you've maxxed out and see if you can delete a factory or dockyard to clear up some space. (Click on the zone and in the bottom left corner you can click on the small X next to the thing you want to delete.)

Nukes are hard to defend against. At the fundamental level they're designed to be an endgame, stalemate-breaking weapon. The AI is actually capable of developing and using nukes, so you should be aware of how to defend against them.

1: Don't let them actually develop nukes in the first place. Wipe them out before ~1945 and you can't get nuked.

2: Don't lose air control. You need 75% control of the airzone to drop a nuke, keep up with their fighter production and they can't nuke you.

3: Beat them to the punch. Nukes are one of the best weapons against getting nuked yourself, as you can target their airports/planes and can damage their production (both civ/mil factories and nuclear reactors)

4: Use everything you can. Build state-AA, airports, and RADAR everywhere you can to cover your air zones. Research AA and RADAR to the max. This will help protect your land, passively shootdown strategic bombers, and give your fighters an edge over the enemy.

5: Spread your troops out. If you have an entire army sitting in your capital city when the nuke hits it, say goodbye to a significant amount of manpower and equipment. Don't give them an easy target.

(Not pictured: Team America, The weapons of the Third Emu War, A Land of Fire, Wunderwaffen)

There are several nuke related achievements, some easier than others. None are very hard, just grindy as you have to get to the end game for multiple countries.

Destroyer of Worlds/Team America - Easy, just play the USA, sit out the war, use your focus tree to get two research bonuses (on top of Oppenheimer and the decisions to get German/Italian scientists), spam out a bunch of fighters and strat bombers and drop where ever you feel like it. I'd suggest Paris, to also get the Team America achievements.

Duke Nuked'em / Tojo Shot First - Just play normally, try to finish off the Allies before the USA can joins. Get naval access from south american countries, land where ever you can, and push hard. You just need air control for a second, don't worry about taking the entire country.

Our Words Are Backed With Nuclear Weapons - Now possible "base game" with the inclusion of Together for Victory as a free DLC. Make sure you get the Quit India focus completed and just slog through. Once you have a nuke, you can go after Japan/Siam if they're still alive, or go after the Soviet Union or China.

Med plutonium (1/2) - Switch to fascist and invade the other country early as you can. (Or just join the Axis and have Germany help.) Wait long enough and release them as a puppet, kick them out and nuke them.

The weapons of the Third Emu War - Trickier than most other achievements, it might be possible via civil war but it's probably easier to let Japan invade you.

A Land of Fire - Nuke Tierra del Fuego. It's the southern most part of south america. Not hard, just grindy.

Wunderwaffen - Technically a nuke achievement. You don't actually have to drop any nukes, just research all three nuke techs (and rocket/jet techs) Easiest as the USA due to the significant number of research buffs and its ability to sit out the entire war.