[Mohammed El-Shahawi]

I would even argue that possession of missiles isn't much good, unless your missiles at least equal the numbers (and megatonnage!) of your adversary. In fact a missile launch gives away the position it was fired from immediately, and the response would come within minutes.
This new stratgic doctrine doesn't leave tell-tale missile launches. As you have correctly observed, finding a deterrnece to it is not easy. The only solution is pre-emptive military action.
I don't understand, at this point, why this case has not been made. I can only imagine it's because the US does not want to appear weak. Explaining why we waited for a year to strike Iraq might be rather, shall we say, awkward.

[Mitchell]

In fact a missile launch gives away the position it was fired from immediately, and the response would come within minutes.

Exactly. Even if it works, it leaves you open to retaliation, since the point of launch will be obvious. (There may be some ways around this, such as launching from submarine, but they'd be awkward, especially for a third world country operating on a shoestring.) Missiles are expensive, too.

I don't understand, at this point, why this case has not been made. I can only imagine it's because the US does not want to appear weak.

Here are some possibilities:

1. There may have been a genuine difference of opinion within the U.S. government as to whether a change in strategic doctrine was needed (Cheney vs. Powell?).
2. The U.S. may also be very uncertain as to whether there is actually a strategic solution that works; if there's not, then we certainly don't want to advertise our vulnerability.
3. The solution may involve substantial military preparation, and we may be quite vulnerable in the meantime.
4. Finally, the solution may involve a very sudden, overwhelming, surprise attack. In that case, we don't want to tip our hand at all, not even by acknowledging the seriousness of the threat.