When it comes to ballistic missile defence, I'll leave that to Jim.
But this is what 9/11 taught us about the nature of states and nature of threats: that they can be both state based and non-state based. Also, this is why, with the increased concern on homeland security, NORAD now has to worry about state-based threats and also non-state based threats. They're still learning how to track this. NORAD is acutely aware of the need to be prepared for both types of threats.