Yeah, the same 60's technology that landed us on the moon.
I don't mean to be flip, but your logic is...well...illogical. A defense system can work against rogue missiles from terrorists and accidental launches, and we need it...but it is useless against this "60's technology" that can quite nicely erase us from the planet earth. And it will remain useless against an all-out overwhelming nuclear attack...in our lifetimes and maybe even in our children's lifetimes..
Methinks you have too much faith in "modern" technology. And many here have way too much faith in the charity of the Russians!
I don't have faith in technology at all. I believe ICBM's will eventually -- Meaning within the next 20 years, be rendered obsolete except by seaborne very-short-notice platforms like "boomer" submarines.
A far larger threat exists in the much less attention-getting forms of delivery, such as a merchant ship pulling into port with a nuke in its hold, or one being smuggled in with a shipment of coffee beans from South America.