Why bother with Sarin? A competent terrorist could cook up any number of equally lethal agents with off the shelf ingredients. Look at what two barely trained kids managed to pull off with a pressure cooker and some fireworks. Now imagine a couple of dozen serious professional types could do.
It used to be that nukes were the only thing anybody ever worried about, because bio-weapons aren't worth crap (we don't know enough about biology to fashion bugs that are simultaneously virulent and viable) and chemical weapons have, on a pound-for-pound basis, less killing power than high explosives. Then either Clinton or Bush decided that we had to gin up some other reason than preventing Saddam from overrunning the oil-rich Gulf kingdoms for keeping the no-fly zone over Iraq, and came up with the Weapons of Mass Destruction canard that covers both biological and chemical weapons. Nukes are the only weapons of mass destruction in existence, and it's really unfortunate that we've further diluted the definition to the point that it now includes the home made bombs used by the Borat brothers.
“two barely trained kids” ... Let’s hold off on exhonorating the professional murderers. These two ‘kids’ are likely only two of a rats’ nest of Is Slime murderers. Mutt and Joker didn’t pull this off alone. There are several indications now that at least five were on the street to accomplish this murderous act.