4 ms·

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 b

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.

gpderetta 4y ago
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.
- nickff 4y ago
  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.
  - gpderetta 4y ago
    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.
    - nickff 4y ago
      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.
      - aerostable_slug 4y ago
        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.
  - aerostable_slug 4y ago
    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.
    - nickff 4y ago
      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.
      - aerostable_slug 4y ago
        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.
less_less 4y ago
> 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.

gpderetta 4y ago

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.

nickff 4y ago
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.
- gpderetta 4y ago
  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.
  - nickff 4y ago
    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.
    - aerostable_slug 4y ago
      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.
- aerostable_slug 4y ago
  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.
  - nickff 4y ago
    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.
    - aerostable_slug 4y ago
      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.

less_less 4y ago

> 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.