A great thread below on ABL, and it's nice to hear some skepticism from someone (R.L.) who actually has some technical background in the field for a change.

It should be pointed out that a robust missile defense system, like an antiaircraft defense, has to involve several technologies and techniques at a number of points in the flight of a missile. There is no single "magic bullet" that can do the whole job effectively by itself. I have studied many concepts, some as complex as orbital platforms, and some as simple as the "hedgehog" defense.*

An ABL can be part of such a system, but obviously it leaves major gaps. An anti-missile missile system, like they are working on for Alaska, is another part of a complete defense. Orbital systems could be a third part, but we need cheaper access to space to make it work.

It continually surprises me that many people think the entire idea of a missile defense is useless. Often the rationale is that if it doesn't work 100 percent of the time, why bother?

My take on it is if they deploy a system that only works 20 percent of the time, it's infinitely better than no system at all.

*The "hedgehog" concept was specifically designed to stop warheads aimed at hardened facilities like missile silos. Such warheads actually penetrate the ground before exploding (an airburst does not bother most hardened facilities much). It consisted of a forest of tall sharpened metal spikes covering the entire area a foot or so apart. Punches a hole in the warhead as it hits the ground...and you don't have to mess with a nuclear warhead much to keep it from going off right. Would have been weird as hell, but a lot cheaper than almost any other concept, and a reasonable protection against a first strike.