The problem that this brings up is that Iraq (or anybody else with anthrax) will have a strong incentive to use it before their WMD is essentially neutralized. There's a very unstable period while the civil defenses are being developed and installed.
It's just like the worry that construction of an ABM system by Country A would encourage a first strike against Country A before the system is completed, since it's Country B's last chance (and since B would worry that once the system is completed, A could stage a first strike with impunity).
It is very difficult to see a solution to this interim problem.
And guess what? There's absolutely nothing we can do about that. That's just a fixed, operational constraint, the real-world consequence of Clinton's fecklessness and Annan's duplicity. We can attack now and face the near-certainty of a massive retaliation against which we have no defense, or we can string things out until we have some way to blunt the threat. Guess which option we're going to take.