Jack Hitt had an excellent article in the previous issue of Rolling Stone about the farce and the fraud of national missile defense. Robert Farley, commenting on the piece, notes the apparent lack of a real strategic rationale for this system-that-doesn't-work:
The utility of a missile defense system has to be evaluated based on its value added over a basic deterrent posture. At least one reason (and not the only reason) that nobody launches missiles at us now is that we would respond by destroying the offending state. The missile defense assumes that deterrence will fail, but its advocates offer no compelling reason for why it would fail; apart from indefensible claims about the suicidal tendencies of the North Korean or Iranian leadership, or very tendentious arguments about terrorists acquiring ICBMs (seriously, if Al Qaeda had a nuke, why would they bother to put it on an ICBM?), there's just not much there. The most sensible case is the "hostage" argument; North Korea might invade the South, then attempt to deter US intervention by aiming a nuke at the West Coast. It's the best argument they have, but it doesn't amount to much; it still requires the North Korean (or Iranian, or whomever) leadership to be suicidal. But even if the argument were compelling, the missile defense would have to be 100% effective; what President would act if she seriously believed that there was a 10% chance an American city would be destroyed?
Unfortunately, I think Farley's thinking on this may lack imagination. Nobody will quite articulate it in this manner, but the purpose of NMD, it seems to me, is to facilitate American first strikes -- either nuclear or conventional depending on the adversary. The basic logic of the right's hegemonist worldview is that the United States needs to maintain the ability to effectuate "regime change" anytime and anywhere. Only NMD can really make that possible.