It doesn’t matter how valuable the thing is that’s being protected. If the interceptor costs more than the missile it shoots down, then a peer adversary can afford to overwhelm your defenses.
We did this during the Cold War where the things being defended were entire cities. Obviously an interceptor that costs a few million dollars is worth orders of magnitude less than an entire city. But if they cost more than an ICBM then the enemy can just out-build you and they don’t work.
I think the political fight around SDI/Star Wars gave people the impression that shooting down ICBMs was just not technologically possible, or it was but evil politicians decided that having guns to each other’s heads was preferable to defense. Fact is, there were technologically viable interceptors in the 1970s. The US deployed a system for about six months to defend missile fields in the northwest. The Soviets deployed one defending Moscow that still exists to this day. The British made it their mission to ensure one of their submarines could overwhelm those defenses and ensure the destruction of Moscow and they succeeded. The British! The US didn’t even have to do anything special.
SDI/Star Wars wasn’t about figuring out how to shoot down ICBMs. That was already figured out. It was (ironically, given the costs) about figuring out how to do it cheaply so that it could actually stop a peer enemy willing to outbuild your defenses.
The US has defenses today that can take down Chinese or Russian nuclear missiles. There are only a few dozen interceptors, while those nations have hundreds of missiles. The interceptors cost a lot less than a city, so isn’t it worth building more? No, because they cost more than the enemy’s missiles, so if we add more, they can add more too, and always be able to overwhelm them. Hence the system exists to defend against rogue launches or rogue states, not an all-out attack.
We did this during the Cold War where the things being defended were entire cities. Obviously an interceptor that costs a few million dollars is worth orders of magnitude less than an entire city. But if they cost more than an ICBM then the enemy can just out-build you and they don’t work.
I think the political fight around SDI/Star Wars gave people the impression that shooting down ICBMs was just not technologically possible, or it was but evil politicians decided that having guns to each other’s heads was preferable to defense. Fact is, there were technologically viable interceptors in the 1970s. The US deployed a system for about six months to defend missile fields in the northwest. The Soviets deployed one defending Moscow that still exists to this day. The British made it their mission to ensure one of their submarines could overwhelm those defenses and ensure the destruction of Moscow and they succeeded. The British! The US didn’t even have to do anything special.
SDI/Star Wars wasn’t about figuring out how to shoot down ICBMs. That was already figured out. It was (ironically, given the costs) about figuring out how to do it cheaply so that it could actually stop a peer enemy willing to outbuild your defenses.
The US has defenses today that can take down Chinese or Russian nuclear missiles. There are only a few dozen interceptors, while those nations have hundreds of missiles. The interceptors cost a lot less than a city, so isn’t it worth building more? No, because they cost more than the enemy’s missiles, so if we add more, they can add more too, and always be able to overwhelm them. Hence the system exists to defend against rogue launches or rogue states, not an all-out attack.