The operative word in there is 'nullify', anything over '0' is not acceptable, and just about everybody agrees that 100% kill rate isn't going to be achievable. So effectively this shield will do exactly nothing, the only thing it guarantees is that if there will be an attack it will be a lot more massive.

Some thing during the cold war, the stockpiles were enormous, not because we needed the power to destroy the world several times over, but because launch facilities might be destroyed.

Also, first strikes will be directed against the areas involved in the missile shield, because after that the rest is wide open.

I see the whole missile defense shield as an attempt to revive the cold war because it's good for defense contractors, those guys made untold billions.