Early missile defense system concepts were nuclear, because it was assumed that was the only way to ensure that a payload delivered to the right neighborhood would take out the missile. This would have resulted in so much collateral damage that it was abandoned early on, and gave a bad name to the concept of defense against missiles per se.

Thus, it was a breakthrough in missile defense when we developed (and continue to improve) the capability to guide projectiles with precision. This allows us to not only not use nuclear explosions, but to get away without using explosives at all. The high speed of the interceptor provides it with sufficient kinetic energy to kill the target from the collision alone.

This has apparently had a nice spinoff for a war in which we’re trying to minimize collateral damage. I don’t know if we’re doing this, but the Brits have come up with a bomb with no explosives. It’s basically just a thousand pounds of concrete which, when dropped from a height to a precise target (using the same smart guidance techniques as more conventional munitions), can do a lot of damage, but without having to explode. It’s like something that ACME might manufacture, except it really really works.

The terminal velocity on one of these things would be several hundred miles per hour, I’d guess, given the density. I wouldn’t want to be in a tank in a narrow city street when one of these things falls on it, but it’s quite possible that one could be standing next to it when it occurred, and not be injured, or even have overpressure on the eardrums. But you definitely don’t want to try to fair catch it.

Saves money, saves lives. Cool.

So we may be able to use such weapons quite surgically, even within a city. We may find out in the next few hours.