All of which are extremely difficult to store, manage, and maintain. I'd bet that there would be accidental contamination of the terrorists long before they'd be able to unleash thier weapons. Frankly, I just think that the threat of a bio/chem attack on the U.S. is completely overblown.
Chem/Bio weapons aren't necessary to cause wide-spread panic or damage. We've seen what can happen with a small fire in a night-club, or a bottle of gas on a train, or even box cutters.
We lose 100,000 people per year in this country to medical mistakes - I'll spend a lot more time and energy double-checking my doctor's recommendations instead of worrying about attacks from drones.
The real target is out economy, which can easily be brought to a screeching halt whether 1,000 die or 100,000 in a WMD attack.