It's been known since the 1960s that effective anti ballistic missile defense is impossible.

cpgxiii 12 hours ago | parent | next [-]

There are several different levels of ballistic missiles.

ICBMs, for which the GBI is intended, are the most challenging to defend against and show the least interceptor success.

In contrast, we do have some pretty definitive evidence that theater and "lower" MRBM/IRMB ballistic missiles can be intercepted successfully. If you define "effective defense" as "most missiles that would cause damage are intercepted", then it is clearly possible with current technology. If you define "effective defense" as "all missiles are intercepted", then it remains beyond the current technology.

	▲	hedora 10 hours ago \| parent [-]
		If you define "effective" in terms of cost ratios: R = (cost of defense system + cost from failed intercepts) / (cost of attack system) then N < 100 is well beyond current technology, regardless of whether the defense system is perfect or non-existent. There's no magic Pareto-optimal point where investing the right amount in missile defense means that starting a war against a medium-sized country makes economic sense. Russia figured this out in Ukraine, and the US figured it out in Iran. Israel's genocide worked pretty well tactically, but is a long-term strategic disaster. If the US continues to be a democracy, polls say that it will cause us to withdraw support sometime this decade. Also, it only works if you have an incredibly asymmetric fight.

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trollbridge 12 hours ago | parent | prev [-]

A lot of things involving rockets and putting things in space have changed since the 1960s.

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BoredPositron 12 hours ago | parent | next [-]

Observability has changed in most other ways we have regressed.

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XorNot 12 hours ago | parent | prev | next [-]

That's true. And while I disagree with the parent comment, ICBM interception remains enormously problematic and likely will remain so until directed energy weapons get really cheap.

Fundamentally the rocket equation and orbital dynamics really fight you on this.

It's a lot less "can't be done" versus "would be financially untenable to build and maintain even when the objective is nuclear defense".

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skywhopper 12 hours ago | parent | prev [-]

Have they, really?

* Small rockets can now land themselves.

Anything else?

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sumtechguy 12 hours ago | parent [-]

Computer guidance? Better materials? Better telemetry?

	▲	pwndByDeath 11 hours ago \| parent [-]
		Still short amount of time to make a decision based on very messy data