This is just a little bit nuts. It's a neat technological trick to be able to shoot down an incoming missile with another missile, but all this back and forth communication looks like trouble. I mean it's nice to know what's going on, and it's nice to keep everyone informed about what's going on, but a simpler if-you-see-it-shoot-it rule might be more reliable. Of course, just because you can see it does not necessarily mean you can reach it with your defensive missiles, you might have to call someone who is within shoot-down range.
The bigger problem is that you only have a few seconds, maybe a couple of minutes at most, to react or you could have a catastrophe on your hands. And how often does one of these missiles get launched? Never, we hope. Meanwhile we need some number (dozens? hundreds?) of people watching and waiting for someone, anyone, to step out of line. Maybe they have computer systems that will alert them if anything happens, so all these people need to do is show up sober for their shift and listen for the alarm. Still, if nothing ever happens I can imagine that they could easily forget just what that alarm horn is for.
Right now I think we still depend on some human making the decision to launch the anti-missile missile, but how long before we get bored and turn that job over to Skynet?