There was a study during the cold war that looked at the idea of high altitude detonations to fry the incoming russian nukes just before turnover during midcourse flight. The neat thing about using nukes as interceptors is that close is ok and the emp fries the missiles guidance system.
Mid pacific for NKorea missiles doesn’t even harm the US. The Nike Hercules even had nukes for terminal defence. Better your nuke exploding at 100,000 ft plus than their nuke going off over your city at 2500 ft.
Lofting one or two nukes is a no win for N Korea, which is why we can’t let the pudgy boy king build 50 or 100 missiles and warheads.
They actually deployed a nuclear missile as part of a 50s / 60s era system for bomber defense.