The details are beyond my expertise, but the EMP, IR redout, and radar blackout effects would depend on the characteristics of the nuclear warhead, as well as the position of the detonation. (EMP effects only take place at certain altitudes.)

There is also the matter of where the detonation would take place. With a GMD-type system vs. a North Korean RV headed for North America, it would take place over Russia or the Russian Arctic. As you note, the A-135 isn’t quite so leggy.

Having said that, it is important to note that GMD has always been a hit-to-kill system. I don’t believe that nuclear interceptors have been entertained seriously in the U.S. for decades — probably not since the shutdown of the Safeguard system in the 1970s. Wait — I’m forgetting about the LoADS idea of the early 1980s. This would have been a nuclear-tipped system that would defend MX missile fields. It was never built. After that, the idea went out of fashion in the U.S.

Not to mention the fact that the A-135 system is only intended for the defense of Moscow, and doesn’t seem to have a much larger coverage (and is definitely not-mobile, mor movable).

I’m no physicist nor engineer, though…