A few "what if" thoughts on Anthrax Theater.
  • Is this a failed terrorist attack?
  • Is it a test bed for a future attack?
  • Is it a diversion for an alternative mode of attack?

Regards the last option, some thoughts.

Postal delivery of biohazards is a relatively low-cost mode of attack. It can be conducted at low cost, can be launched from any location on the planet, can target a broad range of locations with near simultanity, and if appropriately launched, can achieve great public effect. Perfect cover for the sort of distraction you propose.

Of course, the question then becomes: what is the real attack?