I think it is a safe assumption that if North Korea were to fire a missile at us it would be equipped with counter measures.
the most recent missile defense shield that was being developed was meant to protect us from rouge missiles, older missiles from the former soviet union, developed 50 years ago. I think right now we are more likely to be hit from a country like North Korea or Iran who will build their own missile rather then buying an older one.
if you look at the program, there are over 100 companies involved, all with contracts, they get paid even if it fails, and this has been going on for 20 years now. its a mess the way it has been managed.
I think its time we take a step back from this, assess our needs, (I do think we still need this) but take a smarter approach. there is no sense in spending all this money for an out dated system.