Shooting down a missile capable of traveling to any point on the Earth is quite another. You probably need to fire some hyper-sonic missile at it withing about 30 seconds of lift-off, and then actually hit it withing about 90 seconds of lift-off, or the bird has gone bye-bye forever. This is HIGHLY improbable. Every single variable would have to align 100% ideally in order to do this. I’m of the belief that this is, practically speaking, impossible.
Shooting down a missile/satellite with an air-launched missile dates back to the mid-80’s -
https://en.wikipedia.org/wiki/ASM-135_ASAT
Technology has progressed in leaps and bounds since then.
I didn’t say it was new or impossible, just difficult. Everything has to work just right. Yes, we’d be better now than 30 years ago, but it still isn’t easy.
It is also one tool, part of a multi-layered defense. I do hope that we pursue it, vigorously, but let’s just be realistic.