The fact is that there are few fully effective defenses against ICBMs or reentry vehicles like this. We have done pretty well in exercises hitting one in tests....on test day.
That’s a far cry from dozens, or hundreds of missiles incoming, with no notice, where the test missile defense ship isn’t in position, sitting on ready.
This is something we should probably consider when we think about starting conventional wars with Russia. This principle served us well for decades in the cold war.
What served us well during the Cold War was mutually assured destruction (MAD). Neither side took seriously the effectiveness of an ABM system against a full-on attack by MIRV missiles.