Tony Andragna comments:

Unless you can convince me that an anti-missile defense system would be 100% effective in operation, then I’m not comfortable with it’s utility – even one missile getting through would result in deaths to numerous to write-off as an “acceptable failure rate”.

Even accepting your premise that we can’t make a leak-proof defense (we can, at least against anyone except Russia, and eventually, we can defend against them as well–it’s just a matter of building enough redundancy into the system), would you prefer that all missiles get through, instead of only one? That’s the consequence of having no defense, which is where we’re at right now.

I think that you’re assuming that if we don’t build a defense, they (any they) won’t build missiles. What is the basis for that assumption? In fact, building a missile defense reduces the utility of building missiles, since it minimizes or zeros their value.

There are obviously a lot of implicit assumptions in this statement, but debate over these issues has been going on for literally decades, and there is a vast literature available on it, including extensive game theory analysis. You (and many readers) may not be familiar with it, but it’s been argued into the ground, though there remains no consensus.

My experience is that ultimately (and I’m not accusing you of this), the most die-hard opponents oppose it not because it won’t work, but because it will, and the arguments are just rationalizations for their positions. They are uncomfortable with the United States being “too powerful.” Madeleine Albright herself fell into this camp, of guilt over being the only remaining superpower.