eli5: why can’t we intercept nuclear missiles?


eli5: why can’t we intercept nuclear missiles?

In: 1

From what I have learned, you have to destroy them before they reach their descent because the ballistic speed makes it near impossible.

I would assume that whoever fires first gets the advantage to some respect.

Edit: Assuming you meant ICBM

We can, in limited circumstances. Mostly though it’s very difficult. Ballistic missiles travel extremely fast and they’re very small. In order to destroy one, we have to intercept it with something equally fast and equally small and we have to track its speed and position with perfection. If we’re off by even a tiny amount, the intercepting missile will miss. It’s like trying to shoot a bullet out of the air with another bullet.

We can, just the risk is certain other sides might simultaneously lob a thousand or so of them at us, at which point even a ~99% success rate in shooting them down means a dozen cities still get nuked.

With ICBMs the issue is that they tend to be launched either from well within enemy territory or from submarines somewhere in the ocean you don’t know at the time. Both of these makes catching the missiles on the way up very difficult or impractical.

Once they are “up” they are in space and outside of the reach of most kinds of attacks. Most missiles can’t even reach space at all or maneuver without air, much less intercept something in a suborbital trajectory.

On the way down a single ICBM can likely split into 10 separately targeted warheads along with another 90 decoys which try to look as much as possible like warheads. This greatly increases the resources needed to devote to intercepting the strike, as if you confuse a decoy with a warhead you are wasting your defensive missiles. On the other hand not shooting down what you think is a decoy and being wrong means a city being flattened.

That is even if you can shoot them down at all. An Iron Dome missile goes about 500 mph, which is roughly the speed of a cruise missile. A typical fighter jet can go around 1500 mph or mach 2. A Terminal High Altitude Area Defense (THAAD) system designed to shoot down ICBMs on reentry has missiles that go up to 6,300 mph or mach 8.2!

But the ICBM warheads are going to be entering the atmosphere at around mach 21 or in excess of 16,000 mph. That is absolutely *screaming* fast and it doesn’t leave a lot of time to react. From launch to hitting the target it only takes about 30 minutes.

Quoting myself some months back in response a similar question:

“Practically, shooting down an ICBM is a bit like shooting a bullet with a bullet. There are systems that can do it on a limited scale, but it’s still not hard to deploy countermeasures like decoy missiles/warheads, or simply overwhelm missile defenses with a huge number of missiles. To your question, one nuke might be stoppable depending on where it goes, but are you willing to accept a 25% chance of your capital city being vaporized? Even 10%?

Also important, missile defense is controversial. The whole theme of the Cold War was mutually assured destruction–if you nuke me, I nuke you, we both die, so why bother. If any nation can nuke another without fear of attack because of missile defense, it now has an overwhelming power advantage. Rolling out a serious missile defense system would be considered an aggressive act that attempts to establish nuclear dominance.

ELI5: You and your brother each have a baseball bat, and have agreed not to hit each other because you know everyone will get hurt. If your brother puts on a helmet and says “Don’t worry, this is just for defense,” would you be concerned?”