...It's about preventing missiles in the first place. And in that respect, a missile defense shield, regardless of how well it works, is infinitely worse than nothing at all.

First, there is the question of what, exactly, we are defending ourselves against.

• We're not defending ourselves against terrorists -- acquiring and using missiles, for them, would be infinitely more expensive, difficult and traceable than simply rowing a warhead into a harbor or flying it in on an airplane.

• We're not defending ourselves against Russia, China, France, or any other major ICBM-weilding country, for even the most ambitious missile defense system could only take out half a dozen warheads. All the major powers have scores to thousands of ICBMs; a missile defense shield wouldn't amount to a hill of beans in the face of that.

Ostensibly, we would be defending ourselves against "rogue states" with very limited ballistic missile capabilities, that were nonetheless capable of hitting the United States. Practically speaking, there is only one country which has that capability or is likely to have it: North Korea. So, we would be defending ourselves against them, right?

Wrong. Because there's nothing defensive about it.

What's defensive is this: that we have over 2,000 nuclear-tipped ICBMs, ready to fly at a moment's notice. If North Korea were to, say, nuke Seattle, then half an hour later every single North Korean city, town, village, railway siding, and hand-pumped well would be vaporised. Everything north of the 38th parallel would be reduced to so much radioactive glass, and that is why North Korea will never, ever nuke Seattle. The DPRK might be evil, but it hasn't held itself together by being suicidal and stupid.

On the flipside, if the US were to, say, invade North Korea, then half an hour later, Seattle would likely get nuked. That's why we're never, ever, going to invade North Korea.

Unless we have a missile "defense" shield. Then we can invade North Korea without suffering any consequences at home.

That's why there is nothing defensive about "missile defense": merely developing a missile defense shield regardless of how well it works, conveys an unmistakable, purely offensive message. It says that "we are intending to invade you, and there is nothing that you will be able to do about it."

Of course, there is something the North Korean regime can do about it. They can:

• Dramatically increase their production of nuclear weapons and ICBMs, and the sophistication of their countermeasure systems, in order to circumvent the pathetic limitations of a missile defense shield.

• They can develop alternative, non-missile technologies for delivering payloads to the US.

Towards this end, they can forge ties with terrorist organizations who have a common interest in delivering such payloads to the US.

The first of these has already happened; who knows what the status of the of the other two are. Perhaps it can be argued that the evil North Korean regime would do these things anyways, but there is no doubt that the US's breaking of the ABM treaty and development of a Missile Defense Shield has greatly increased the pressure for them to do so. And the even if they were going to do so anyways, the presence of a missile defense shield would do nothing to protect against such measures. In fact, it may make us less safe, by diverting massive amounts of funding away from other, more effective strategies (like, say, human intelligence).

And that is why a missile defense shield that only works 20% of the time -- or even one that works 100% of the time -- is infinitely worse than none at all.

Cheers,

Nathan.