This. The mutually assured destruction doctrine works because both parties knows that the party which does the first strike will be obliterated by the other party's second strike, so neither party wants to be the one to strike first. However, if party A should get too good of an ICBM defence system, mutually assured destruction would stop functioning; party A could conceivably fire a first strike with the knowledge that party B wouldn't be able to retaliate with a second strike. This would make it in party B's interest to do a first strike before party A's anti-ballistic missile systems are functional (EDIT: or something like that; essentially, it breaks the entire MAD mechanism, I shouldn't make it sound like any particular outcome is likely.)

There was a whole anti-ballistic missile treaty which banned the US and the USSR (and then its successor states) from developing anti-ballistic missile systems. George W. Bush withdrew the US from the treaty in 2002.

Further reading: https://en.wikipedia.org/wiki/Anti-Ballistic_Missile_Treaty

MAD isn't a doctrine. US doctrine is simply Assured Destruction. Russian doctrine is escalate to deescalate. Neither doctrine actually contemplates that mutual destruction is a good thing.

The wikipedia article consistently refers to it as a doctrine: https://en.wikipedia.org/wiki/Mutual_assured_destruction

> Mutual assured destruction (MAD) is a doctrine of military strategy and national security policy ...

I'm unable to find anything about the "Assured Destruction" doctrine which isn't about MAD. If you have some links I should read to learn more, please do send them. But presumably, the US's official doctrine is that if Russia sends in a first strike, the US will retaliate with a second strike? And presumably Russia's official doctrine is the same? If that's the case, isn't that just the MAD doctrine, even if it's under a different name officially? Or has both countries officially said that a first strike won't be followed up by a second strike?

https://en.wikipedia.org/wiki/Military_doctrine - Military doctrine is the expression of how military forces contribute to campaigns, major operations, battles, and engagements.

MAD is a game theory construct. It may inform doctrine, but it doesn't actually dictate how we employ forces. US doctrine can be found in the nuclear posture review : https://media.defense.gov/2018/Feb/02/2001872877/-1/-1/1/EXE...

It amounts to : the primary point of the US arsenal is deterrence. As such, we will assure that we can destroy the enemy as necessary.

Russian doctrine had explicitly contemplated the first use of nuclear weapons "in response to large-scale aggression utilizing conventional weapons in situations critical to the national security of the Russian Federation." So if they get in a war and start losing.

The critical part of MAD is a so called balance of terror. But the US doesn't use nuclear weapons because it's afraid of getting nuked in return, and Russia believes that they can win a nuclear war. So it's both not doctrine (because it's not how either military plans to use forces) and not real (because the preconditions don't exist).

I can understand each logical step of MAD, but if you look at the whole picture it really does seem kind of silly. Like, why not both agree to allow the other to place a stationary gigantic nuke in each major metro area under the control of the other, and call it a day? Of course that seems absurd, but it's not more absurd than not developing anti-ICBM weapons. And think of the savings it could have produced? I haven't looked at actual numbers but there has to be a phenomenal amount of resources that have fueled MAD over the last ~60 years. Now that I think about it, an even more cost effective measure would be the ancient practice of exchanging hostages. Each top political or military official has a loved one live in the other country while they're in office. Also sounds absurd at first, but probably would have been just as effective at avoiding war which is all MAD is good for anyways.

May as well ask why make weapons at all. The absurdity of it has been well documented in the art of the Cold War in the twentieth century.

> Like, why not both agree to allow the other to place a stationary gigantic nuke in each major metro area under the control of the other, and call it a day?

Because then the solution would be to disable all of the other country's nukes simultaneously and then trigger your own.

Yeah, it's obviously not great. But it seems to be a kind of stable local optimum, where any step any single party could independently take to get rid of MAD would be against that party's interest. Honestly, barring widespread global nuclear disarmament, it feels like the nuclear weapons hat is out of the bag -- and at that point, it's a choice between MAD and nuclear armageddon.