radar arrays and space or ground lasers, etc. but essentially lasers.
but a new age of war will be upon us. When all of the weapons get used up and the factories making them destroyed, and the radar installations and satellites fried with EMP's, then again it will be up to 17 year-olds fighting the fat man's war.
At some point, any missile defense system is going to have to estimate damage and pick some targets, but leave others. When there are multiple vehicles,.you're pretty much fucked.
The idea that a missile defense system can prevent full-on nuclear warfare is false. It's meant for one-off strike deterence, not for full on war.
If you don't stop a nuclear launch vehicle when it's on the ground or very shortly after launch, your chances at stopping it are slim.
And as it happened someone already did shoot the Pentagon for a little warning message. That's the most likely explanation. But most likely not Russia, just one of their hypersonic nuclear missiles probably from the Kursk, without the warhead.
Missile interceptions with lasers isn't easy, and if you have two working lasers for interception, the adversary can always try firing four missiles at once.