Yes, we haven't been at war with the No. Koreans, yet. But they've been preparing for one as evidenced by their continued ballistic missile and nuclear bomb tests. So at best its sort of working, if you believe that continued activity of the No. Koreans. As for missile defense, yes, it is indeed far from perfect. But then what in this world is perfect? As I said (and I have no illusions about the state of missile defense), a fighting chance of intercepting an incoming ballistic missile is better than zero chance of an intercept, which is what you apparently advocate. And yes, missile defense is expensive and may not yet "deliver", but frankly, if I can stop the delivery of a No. Korean nuclear-tipped ballistic, well, I'll take my chances with missile defense rather than going totally defenseless and being at the mercy of the No. Koreans and orbital physics (read, ballistic trajectory).