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Missile defense is NP-complete

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Re: Missile defense is NP-complete

#151

Post by consumer451 »

Voultapher wrote: post #124
maxglute wrote: post #111

>Hence, for one warhead, a defender can launch 4 interceptors and have a 96% chance of successfully intercepting the incoming warhead. >Unfortunately, those numbers are optimistic. This part worth stressing, ceiling for more performant missiles, i.e. faster, terminal maneuvering, decoys are geometrically harder to intercept. Past mach ~10 terminal and functionally impossible because intercept kinematics will break in…

Lasers. No really, near-future laser systems with adaptive optics and good spotting - for example distributed SAR satellites - dramatically shift that balance [0]. [0] https://toughsf.blogspot.com/2025/05/the-laser-revolution-pa...

Lasers are not "all weather" weapons as far as I am aware. Clouds, snow, fog, rain, and just humidity all degrade their performance greatly.

Re: Missile defense is NP-complete

#152

Post by Maken »

captainswirly wrote: post #88
nerfbatplz wrote: post #81

Earlier quoted context omitted.

Technically Iran fires SRBMs and MRBMs not ICBMs. They intentionally gimp their missiles to avoid advertising ICBM range as a way of placating Europe.

[flagged]

ICBM means the missile is able to be launched into other continent (more than 5K kilometers in range), not about its effective warhead. Iranian missiles are fast and efficient, but their effective range is essentially being able to target Israel and the Gulf States, which means they are not ICBMs. Also, the one country in the Middle East who does have ICBM missiles and can target Europe is Israel, not Iran.

Re: Missile defense is NP-complete

#153

Post by dlisboa »

pc86 wrote: post #132
hedora wrote: post #59

Earlier quoted context omitted.

Currently, we're using $1M interceptors to take out $30K drones. This asymmetry is here to stay. The end game probably involves At that point, it turns into a logistics problem that's much easier for the attacker than the defender. Iran's already demonstrated that one successful drone can do $100B-1T in damages, so a hit rate of 0.1% means a 1:100K cost:damage ratio.

What Iranian drone did a trillion dollars in damages? I'm not saying the general thrust of your argument is wrong, quite the opposite. But that's a big number for one drone.

A trillion seems large but it's not that absurd. The drone that shut down 17% of Qatar's LNG capacity is said to have caused 20 billion USD worth of annual lost revenue. They said it'll take up to 5 years to rebuild so that could be 100 billion USD in lost revenue, plus whatever it costs to do the rebuild.

A trillion dollars worth of damage seems possible if spread over some years for some countries in the Gulf where shutting down a desalination plant would cause depopulation.

Re: Missile defense is NP-complete

#154

Post by varispeed »

iso1631 wrote: post #127
varispeed wrote: post #49

Earlier quoted context omitted.

You miss the fact that many adversaries will not act rationally.

Yes, if it was acting rationally the US Would not have spent billions trying to blow up an 80 year old man while massively increasing the price of oil and fertiliser globally leading to economic instability But the US has not acted rationally. It hasn't since January 2021.

There could be a rational explanation if you assume US administration is compromised by Russia and Ayatollah's son wanted him out to assume power. One phone call to Putin, Putin's one phone call to Krasnov and everyone is happy. Son gets the power, Russia gets sanctions lifted, higher oil price, US and allies spend kit that cannot be now sold to Ukraine, Krasnov gets to play the stock market. Win-win-win.

Re: Missile defense is NP-complete

#155

Post by O3marchnative »

gpderetta wrote: post #138
Voultapher wrote: post #124

Earlier quoted context omitted.

Lasers. No really, near-future laser systems with adaptive optics and good spotting - for example distributed SAR satellites - dramatically shift that balance [0]. [0] https://toughsf.blogspot.com/2025/05/the-laser-revolution-pa...

I doubt a MW laser can reliably intercept a reentry vehicle. A lot of energy is lost through the atmosphere when intercepting a warhead in space, from a land based laser. Once it reenters the atmosphere there might not be enough time. You also need to burn through the heatshield that the warhead is equipped with for reentry. Even if you can can deliver enough energy for long enough, there is no fuel to burn and it mi…

> For ICBMs, one idea was to use orbital, nuclear powered lasers to hit the missile on the boost phase.

Author here. Thank you for your insight.

I took some time to read about the recently proposed "Golden Dome" defense system, and what you laid out seems to be the end goal [0]. It's difficult to tell how realistic this actually is. The size of the constellation of satellites needed seems prohibitive, to say the least.

[0] https://armscontrolcenter.org/fact-sheet-golden-dome/

[1] https://www.defenseone.com/ideas/2026/02/space-based-interce...

Re: Missile defense is NP-complete

#156

Post by maxglute »

myrmidon wrote: post #29
jsw97 wrote: post #8

The author explains that this problem is actually adversarial, in the sense that the attacker gets to observe defenses and allocate warheads and decoys accordingly. Thinking of our current circumstances, this suggests another cost of war: our offensive capabilities, as well as our defensive capabilities become more observable. Our adversaries are studying our strengths and weaknesses in Iran, and they will have a muc…

This is absolutely true, but there is a strong counterpoint: You also learn the limits of your own systems and how to operate them most effectively yourself (and better than adversaries can, too). Just to pick a recent example: Russian air defense in the early stages of the Ukraine war was dismal (more specifically: defense against big, slow drones like Bayraktar), despite having sufficient AA capability "on paper"--…

>much more value from validating and improving your equipment and its handling than the actual "cost" of revealing its capabilities to adversaries in almost every conflict.

The value of carrying a big stick is lost when others see the stick breaks after a few swings. There's value in maintaining military kayfabe - revealing hand in sideshows and losing deterrence for main events as result can be much costlier down the line. What was learned that wasn't already known and deliberately avoided in polite conversation?

Re: Missile defense is NP-complete

#157

Post by hedora »

OrangePilled wrote: post #130
quotemstr wrote: post #27

The sole mention of directed energy: > Directed energy has been proposed as a cost-effective alternative, but introduces its own scheduling constraints — dwell time, platform coverage, atmospheric degradation — with similar scaling issues The author is doing the thing where a writer tries to bamboozle the reader into a conclusion without having to prove it by overwhelming the reader with nouns. Life is too short for…

Bearing in mind the three constraints quoted, which of these do you think a country's deployed directed-energy weapons (e.g., US, Israel, Russia) would be useful against: https://missilethreat.csis.org/country/iran/

You don't really have to guess. None of those countries are using directed energy weapons, and they're all repeatedly getting hit by Iranian technology (so they have an incentive to test whatever they have).

Re: Missile defense is NP-complete

#159

Post by hedora »

koakuma-chan wrote: post #143
hedora wrote: post #137

Earlier quoted context omitted.

$1M, but we can only make 600 / year, globally.

From the article, "Each GBI costs approximately $75 million, and as of 2024, 44 are deployed across Alaska and California [3]."

I'm quoting the missile cost. I think they're quoting the launchers + a few missiles.

(Also, lower bounding the cost improves the argument that they're too expensive to be practical.)

Re: Missile defense is NP-complete

#160

Post by falcor84 »

testaccount28 wrote: post #104
falcor84 wrote: post #80

Earlier quoted context omitted.

I think that there's a more general issue here with the US and the West in general having a mindset built up on playing Risk and Civ, which considers the foreign country as a whole as their opponent, whereas in practice, the adversaries are a multitude of individuals, for almost none of whom a surrender is the rational choice, especially (as sibling comments pointed out) when part of their reasoning and authority is…

to be clear: your claim is that the us military is misinformed because key constituents have played too many board games? does hearing it back like that make it seem absurd to you as well?

Well, yes (except that Civ isn't a board game). And no, it doesn't make it seem absurd to me.

My argument is that Western strategic thought (with games being a codification thereof, rather than the source of) generally considers countries as mostly atomic actors that can be defeated - the history of European warfare being filled with "gentlemanly" surrenders followed up by peace treaties, with guerrilla warfare being a very rare exception.

On the other side, the reality in the East is that a state's collapse doesn't end the conflict, but just prolongs it. The army doesn't surrender, it goes home with its weapons and reconstitutes as insurgents. I can't actually think of a single proper surrender of an Eastern country ever, except for Japan in 1945.

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