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The article touches on this in an off-hand dismissive line, but anti-missile technology is destabilizing.

If the anti-missile system is effective, then it allows for a first strike without retaliation. I.e., anti-missile systems are offensive weapons. The largest constraint against using nuclear weapons in a first strike is removed for the party with the effective anti-missile system.

Even if it doesn't work well, or at all, you now need your adversary to believe that you spent billions on an ineffective weapons system. If your adversary is not convinced of this, then they have every incentive to react to (possibly false) alarms sooner. Incidents like the following might have ended differently:

https://en.wikipedia.org/wiki/1983_Soviet_nuclear_false_alar...

https://nsarchive.gwu.edu/briefing-book/nuclear-vault/2020-0...

https://www.nytimes.com/2018/01/13/us/false-alarm-missile-al...

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> If the anti-missile system is effective, then it allows for a first strike without retaliation. I.e., anti-missile systems are offensive weapons.

This is simply false. An effective missile defense system is not necessarily capable of defeating an entire nuclear arsenal of a peer power - easily verified if the number of interceptors is substantially smaller than that power's inventory. The nuclear defense triad extends beyond just ground launched ballistic missiles - bombers, cruise missiles, and submarine launched missiles all offer means to retaliate which a missile defense system alone can not defend against. And finally, the adversary can also develop an antiballistic missile system for exactly the same protection. Of course in the real world such a perfect missile defense system is not possible - realistically there's always going to be too big a risk of some nukes getting through for any rational actor to seriously consider a nuclear exchange. As for the irrational actor, they can not be trusted to avoid mutually assured destruction.

It's like saying a city wall is an offensive weapon because the one city with a wall can attack others without being attacked. Yeah, maybe the very first city to build a wall had a bit of an advantage before everybody else built a wall, but anyone can have a wall without putting anybody in danger.

> If your adversary is not convinced of this, then they have every incentive to react to (possibly false) alarms sooner.

Without a missile defense system, your only hope of surviving nuclear war is taking out your adversary's retaliatory capability - this means a first strike is primarily going to be tasked with doing just that and thus makes launching quickly in response to an incoming strike a necessity. Even if there is a chance it's a false alarm, a limited retaliation might be seen as a more survivable option than waiting to confirm. If on the other hand your opponent has an effective missile defense system, then they have far less incentive to try and suckerpunch you, and thus an unexpected strike can be much more safely labelled a false alarm. Certainly there is no incentive to retaliate faster - what is that going to do but waste missiles? You don't overwhelm a missile defense system with quick retaliation but with massive retaliation. While nowadays some military commanders might entertain the notion of a limited nuclear conflict where a small strike warrants only a proportional retaliation, with missile defenses it's unambiguous that once nuclear war is triggered people will launch everything they've got in an effort to guarantee at least some warheads make it through, and thus reinforces mutually assured destruction.

The wall example doesn't make sense as it is hard to imagine a non exceedingly convoluted MAD scenario where it would be relevant.

Anti ballistic systems are destablizing if you believe you can survive a first strike, your enemy believes you can survive it or your enemy believes you believe it.

It just add many variables to a already deadly calculus.

In truth, effective ABM systems encourage a bolt-from-the-blue strike from the country without ABMs, because they fear the same from their adversary who might be able to ride out a second wave, so theory says hit first. The destabilizing effect is precisely the opposite of what most state.

As others have noted, ABMs usually are easy to count, and the countermeasure is N+1. This is why the UK strategic deterrent is the size that it is: no matter what, Moscow eats a big one.

Exactly. An ABM is likely to be more effective against a second strike, which means that the side without them is encouraged to strike first.

Why do you think that "ABM is likely to be more effective against a second strike"? Do you think the ABM systems are usually deactivated in times of peace? What about in times of tension? Even if I agree ad argumentum, ABMs would encourage first strikes from out of the blue and discourage strikes in times of tensions.

There are simply less missiles to intercept in a second strike as the primary target of a first strike is the nuclear arsenal of the opponent.

You are assuming the first strike successfully destroyed some fraction of the target's arsenal (without the opponent launching before being hit). I am not sure that nuclear strategists would make that assumption.

It would, that's the whole point. That's why we develop ever-more-accurate missiles, and why we quasi-openly advertise their CEP.

If you had missiles with lousy accuracy, you'd never consider a counterforce strike. Do as the Chinese did until recently, and target cities and industrial centers. Counterforce targeting is a cheap and effective strategy. OTOH, look at the United States: Trident D-5 is more accurate than the stock MMIII (it's not openly known how MMIII with AIRS from the MX fairs). We can land RVs so accurately that they may as well have conventional warheads. That's destabilizing — but we tend towards the exceedingly rational in our decisions.

Let us imagine you are a nuclear power A. You do not have ABMs. Nuclear power B does, and you believe they are effective (key point). Logic dictates that you will end up the guaranteed loser on an exchange where A fires first with ABMs backstopping their second strike. Now, you might not lose when B fires first, so game theory says you fire first.

Whoosh missiles fly and everyone loses.

The first strike is always advantaged, in that it may destroy some fraction of the opponent's arsenal; I'm not sure how much ABMs change that.

The advantage is with the clean-up. First strike takes out some amount of launch vehicles. ABMs have a prayer against x-y warheads, where y is the attrition from the first strike (which is nonzero unless you're dealing with a launch-on-warning opponent, which neither the US nor Russia nor China is).

Few powers are really ready to perform launch-on-warning. The consequences for a false positive are too dire to consider, and we all also have a survivable second strike capability (with the possible exception of China, whose submarines are boiled crap run with an Evinrude outboard). And in my estimation, even China would ride out the first wave.

> In truth, effective ABM systems encourage a bolt-from-the-blue strike from the country without ABMs, because they fear the same from their adversary who might be able to ride out a second wave, so theory says hit first.

If leaders care more about surviving than about killing their enemies, then effective ABM (and defense against other nuclear threats) changes plans more for the country with ABM. If you try a first strike without ABM, you're dead whether your enemy has ABM or not (and if anything, you're slightly more dead if they have ABM). But if you try a first strike with a good enough defense, you might not be dead. And first vs second strike makes a huge difference, because destroying most of the enemy's nukes in a first strike is critical to making your defense possible.

It might seem insane to launch a first strike if the defenses aren't perfectly reliable. (Or like, even if they are, since a first strike is certainly murdering hundreds of millions of people.) But during a crisis, if you think nuclear war is coming and might not be avoidable, then the math changes. In that case you're comparing your odds of surviving an enemy second strike to your odds of averting an enemy first strike. Then the ABM makes a big difference to your willingness to push the button.

For the other nation, it might affect their perception of alarms (eg might make them think a false alarm is a true one, if ABM makes an attack seem more likely), and once that alarm goes off it might incentivize a larger or earlier strike to make sure that their vengeance is effective. But in my non-expert opinion it changes plans for the nation with ABM much more.

> Anti ballistic systems are destiblising if you believe you can survive a first strike, your enemy believes you can survive it or your enemy believes you believe it.

That adds stability, not detracts from it. If I am deathly afraid of you punching me because I have no defense, then the moment I think you're going to punch me, I need to punch first. If I can take a hit, then I can wait to see what you were actually going to do. Further, if you think you can knock me out with one punch, maybe it's worth a shot. If you know I'm going to be able to hit you back, then that's far less incentive to try.

Holding matches in a room full of gasoline to deter others from dropping theirs is a terrible strategy. Foregoing a fire extinguisher in the hopes that it'll make people hold their matches tighter is insanity.

> If the anti-missile system is effective, then it allows for a first strike without retaliation.

That's a big if. Current and near-future ABM systems can take out a handful; great if Iran or North Korea decide to take a potshot, but those are opponents the US can essentially take out in a first strike without nukes if they don't mind the massive blowback.

The US has no hope of intercepting all of Russia's or China's nukes anytime soon.

There is nothing inherently stopping Iran or North Korea to build a few dozen MIRV-capable missiles.

Aside from the fact that releasing more than one thing from a space launch vehicle accurately is actually a fair hard thing to do. Which is why multiple satellite buses are considered dual use technology, and export of them is prohibited. Release of said tech to China back in the 90s is considered to be a large player in why they have MIRV ICBMs.

The US doesn't conduct a nuclear first strike, not because it fears getting nuked in return, but because it doesn't want to be seen as the bad guy. The presence or absence of a missile defense system doesn't change this. Also, there's an entire paragraph on why even an effective system won't change this, so long as it's not perfectly effective (which it can't be), because we still end up with one or more nukes landing in the US, and the acceptable number for that is politically 0.

Though I agree with you that the US would not do such a thing, such assertions - even if written into state policy - cannot reassure an adversary. The US is, in fact, the only state which has used nuclear weapons in combat - it was the very first strike.

True, but the change in US attitudes towards being willing to conduct a first strike, and/or being willing to lose a city to a nuke, won't come quickly or secretly.

> it was the very first strike

... 'very first strike' sounds a bit too loaded in the context of Hiroshima/Nagasaki and WW2 as a whole.

It may have been a rash action, perhaps a 'first nuclear strike'.

'very first strike' sounds loaded to the extreme when we consider it was one of the last actions in a multi-year contracted conflict.

If you ever do a first strike, the world the next will changed in such a profound way that would it even matter if you are seeing as the bad guy?

Any leftover sense of moral and sanity is probably more likely to be relevant.

Tactical use of nukes, as opposed to a strategic first strike, is different of course.

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