And not finding these stockpiles doesn't always reassure me. The following information is from Richard Preston's The Demon in the Freezer (edited and summarized for the sake of brevity):
A secret British-American weapons-inspection team toured four of the main Biopreparat scientific facilities in January 1991....They ran into the same problems that the United Nations inspectors would later run into in Iraq. The Soviet biologists did not want to discuss their work and did not want anyone seeing their laboratories in operation. The inspectors were met with denials, evasions, time-wasting bureaucracy, stupefying, alcohol-laden meals that stretched on for hours, snarled transportation arrangements, and endless speeches about friendship and international cooperation. [emphasis mine]
The end result of the visit was that while visiting Vector, a site for the study of viruses, they were told by one of the scientists that work with the smallpox virus was going on there. This, of course, was highly illegal as the only two places in the world that were supposed to even have smallpox were the CDC and the Moscow Institute. The team pressed the issue and was ordered to leave. Later, they were told the scientist was "mistaken." By the way...there were no "stockpiles" found, yet Christopher Davis, the head of the team said "The fact is, they had been testing smallpox in their explosion test chamber the week before we arrived."
Later on, a Soviet defector described "a huge program broken into secret compartments. Very few people inside the program knew it's scope. Because it was compartmentalized and secret, it had the potential to fall apart into smaller pieces, and the world might never know where all the pieces had gone." [emphasis mine]
Jump to three years later.
The Soviets, still busy at work in the Vector site, build "a three-hundred gallon tank that looks something like a water heater." Later, in 1999 visiting inspectors would be told it was for "sewage-treatment." In reality, it was a bioreactor, a breeding ground for viruses grown in a big soup of monkey cells, which could then be extracted along with the liquid in the tank.
A single run of the reactor would have produced approximately one hundred trillion lethal doses of variola major--enough smallpox to give each person on the planet around two thousand infective doses of smallpox. [emphasis mine]
To put that in perspective, the World Health Organization has less than one dose of smallpox vaccine for every 12,000 people on Earth. Not that it matters anyway. The smallpox virus in Vector was likely "heated up," meaning that it was purposefully bred to be resistant to vaccines. The WHO's vaccine would likely be useless.
Do we need to find "stockpiles" of these substances? According to Preston, one MIRV missile is capable of delivering forty-five pounds of smallpox. That's it--forty-five pounds. Seem like a lot? It's not. Preston relates the story of a smallpox infected patient that (before anyone knows what illness he has) disobeys hospital rules and opens a window to smoke. The draft created from that open window acts like a chimney, and funnels the air from the patient's room through the hospital. The breath from that one patient creates nineteen new cases of smallpox over three floors. In a hospital.
Of course, smallpox is one of the most virulent substances to have ever existed. But many of the other biological weapons can be just as devastating. That forty-five pounds of smallpox would have likely wiped out a city before it could react, and without a feasible vaccine, would have ripped through the country and then, depending on how secure the borders were, spread like wildfire into neighboring countries. That's why some of the tightest security in the world protects mere vials of the stuff. A little goes a long way.
So next time you get involved in a conversation about WMDs in Iraq or elsewhere, remind yourself of two things: 1) One doesn't need much to create a great deal of damage, and 2) Even if you have to destroy it to hide it, as long as you keep a little bit you can always make more.
NOTE: All of this is in regards to biological weapons. Chemical weapons are a bit different in that the production is somewhat different, a larger amount would likely be required, and they are generally contained within the delivery area. To the best of my knowledge, no one has suggested that Iraq had smallpox among their arsenal. My examination is merely presented as a "worst-case" scenario. Although I will point out that since the collapse of the Soviet Union, I'm not sure that the idea of buying Soviet smallpox on the black market is any less ridiculous than the idea of buying old nukes. Pleasant dreams.