What we really know about Iraqi weapons production is the situation prior to Desert Storm. There is a lot of uncertainty now because we don't know what was destroyed. But the evidence suggests that the Iraqis have been trying to protect or at least keep remnants of those programs alive, notwithstanding the U.N. inspections.
Chemical and biological weapons are really quite different. Biological weapons are pretty indiscriminate and therefore tend to be more terror weapons than military weapons. They can, if the wind changes, blow back onto your own soldiers. And while they're useful for killing or disabling a lot of people, the weapons' effects often take time, so they're not really useful for combat. Chemical weapons have some of the same dangers as biological weapons, but they have been thought of more as possible weapons. Both the Iranians and the Iraqis used lots on each other in their war.
As to delivery systems for this type of weapon, Iraq certainly has had an interest in long-range missiles. But they have probably not developed any viable delivery system for chemical and biological weapons.
Even if there were no problem with delivering the stuff, the more difficult calculation for Iraq would be: What's to gain versus what's at risk? If they wanted to take the step and actually kill a lot of people, then the question would be: Which scenario do you produce? Do you produce a Lebanon, as in 1980 when the Marine barracks were bombed and we quickly thereafter moved out, or do you provoke a Pearl Harbor and get people to decide that there are really important stakes to be protected? That's the Iraqi dilemma with respect to using these weapons.
I doubt that we have a very good possibility of actually taking out weapons in any air strike we launch. Our problem now is that many of the sites we know, we've searched, and the sites we don't know about, like the so-called presidential sites, we haven't searched, so we don't know whether anything's there or not. We know that in the past the Iraqis had secret facilities. There could today be facilities protected down in deep bunkers. So I think it's hard to imagine that air strikes would do much actual destroying of weapons. The goal is to try and push Iraq back into some sort of compliance.
The real dilemma for the United States is that there's not a very attractive military option. Even if you could use air strikes to take out weapons, you'd run the risk of killing a lot of Iraqis. And if Hussein remained alive, and he most likely would, then he would look like a kind of a hero for surviving. There's also no guarantee that we'd get the kind of access we want, even after air strikes. Saddam Hussein doesn't seem to care a thing about his population. That's another real dilemma.
In some ways, biological weapons are probably the easiest to develop. Their production facilities are best likened to a microbrewery, albeit a microbrewery where, if you make a mistake, you can kill yourself. The weapons are not easy to produce, but they're not that hard either. You have the Tokyo subway case to demonstrate it is possible. Chemical weapons tend to be slightly harder to make, but any country that has a decent chemical industry can probably make them. There is still the challenge of turning substances into weapons, and that's not trivial. Still, if you want to have some particular effect, you can probably find some way to release the stuff into the atmosphere, especially if you just want to kill a lot of people.
As for nuclear weapons, the basic technology for making them is well-known, so it becomes an engineering problem, and the core of that problem is trying to get enough material that actually goes "boom," which is not trivial. There are lots of reports of material for sale from the former Soviet Union. It has been real material, in some cases, but mostly in small quantities. And so the production of nuclear weapons remains on an order of magnitude harder than making biological or chemical weapons. In a country like Iraq, I think it likely they'd say why bother? You'd probably get pretty much of what you'd want with things that are easier to make, such as chemicals and biological agents.
There are certainly other countries we suspect of having an interest in developing biological and chemical weapons. But we caught the Iraqis. We defeated them in Desert Storm and then put them under this international tutelage. So we have with Iraq a kind of consensus and mechanism in the U.N. for dealing with its weapons program. It's not as though American policymakers aren't concerned about the weapons of mass destruction in other places. It's just that this is one place where we knew there was a real interest in them and we saw production and research facilities, and then, after Desert Storm, we had the U.N. mechanism for trying to keep the lid on.