Missile interception and defence has always been a large grift, since the Reagan era "star wars" nonsense, followed by the Israeli Iron Dome. Outside of basic projectiles or slower moving objects, it's incredibly hard to intercept something. Objects traveling at multiple times the speed of sound with the capability to steer themselves (which the latest North Korean missiles are capable of, someone please correct me if I'm wrong) are going to be very difficult to intercept with current technology.

Though I guess it's good to put the theory into practice.