If there is one thing about which all analysts of the approaching war agree, it is that Saddam’s use of chemical or biological weapons constitutes the "worst case." So what is the likelihood that Saddam will employ chem/bio weapons? If he does, how well are the allies prepared to operate in a chem/bio environment?

Some intelligence reports indicate that chemical warheads have been distributed to certain Iraqi units. Since no such distribution took place during the run-up to Desert Storm, many have concluded that the employment of at least chemical weapons is likely this time. Last week, Fox News featured an Iraqi defector who claimed that the use of chemical weapons was a foregone conclusion. This could just be psychological warfare on Saddam’s part.

But we have been engaging in psychological warfare as well, making it clear to Iraqi commanders that we will hold them personally responsible if they launch chemical attacks on coalition troops. Only time will tell whether this approach will work. Psychological warfare aside, there are a number of factors that militate against Iraq’s use of chemical and biological weapons. Although there is a tendency to categorize nuclear, chemical, and biological weapons all as "weapons of mass destruction," (WMD) this characterization obscures many differences among them.

First, in my judgment, Iraq will not use biological weapons. One of the reasons they have not been used in modern war is uncertainty about the effects. Releasing a biological agent could affect the launching side as adversely as the targeted side. In the case of Iraq, it could have a devastating effect on the unprotected Iraqi population, as a biological strain wreaks havoc on both soldiers and civilians and then mutates, rendering any antidote ineffective. It seems to me that, even if Saddam wants to go out in a Gotterdammerung, the risks of using biological weapons far outweigh the benefits. Chemical weapons are a different matter. We know that Saddam has not accounted for a number of chemical agents that the Iraqis could have "weaponized." Chemical weapons can be delivered by tube artillery, missiles, or aircraft. There are also chemical mines. Delivery might be as simple as detonating a 55-gallon drum filled with a chemical agent at a critical road junction or bridge, exacerbating the problems of a formation already slowed down by a water obstacle or by simple congestion. They can be used against logistics bases.

But again, there are many factors that can reduce the incentive for the Iraqis to employ chemical weapons. First, the side that launches a chemical attack faces uncertainty about the effects. Chemical weapons are extremely sensitive to local weather conditions, indeed, microweather conditions. Heat, wind, and humidity all influence the effectiveness of chemical weapons. Because of this reality, it was usually the attacker, not the defender, who employed chemical weapons during World War I, the last time they were used against an armed force rather than defenseless civilians.

Second, chemical weapons are most effective when employed by a prepared force against an unprepared force. If both sides are prepared, there is no net gain to the side that uses chemicals. The tempo of military action will slow, but not stop. Indeed, in a chemical environment where both sides are prepared, Allied forces will still possess substantial advantages. And there is a great deal of doubt concerning how well prepared the Iraqis are to operate in a chemical environment. By most accounts, they are far less prepared for chemical warfare than U.S. troops. This may be the most important reason for thinking that Iraq will not use chemical weapons.

But how well are U.S. troops prepared in case Iraq chooses to use chemical weapons? During the Cold War, commanders often paid lip service to protection against chemical attack, because the conventional wisdom was that nuclear weapons deterred not only nuclear, but also chemical attacks. There were gas masks but not much in the way of chemical protective suits.

Training for the most part consisted of an annual or biennial trek to the "gas chamber," where soldiers and Marines would don their gas masks in a cloud of such riot control agents as CN or CS gas We learned how to self-administer atropine, an antidote for certain nerve agents. This was pretty much it for the average serviceman or woman. Of course, the Army also had specialized chemical units, mostly for detection and decontamination. And artillerymen got to learn how to plan for the use of chemical weapons, as I did as a young Marine captain attending the U.S. Army’s Field Artillery Advanced Course at Fort Sill, Oklahoma three decades ago. What struck me then, and probably influences my thinking now, is how difficult it was to ensure the effectiveness of a chemical-weapon attack.

Things have progressed a great deal since the end of the Cold War. Recognizing that traditional deterrence might not work against a Saddam bent on using such weapons, we now take chemical-warfare training seriously. The Abrams tank and the Bradley fighting vehicle are designed to operate in a chemical environment. So are many helicopters, fixed wing aircraft and ships. Of course not everyone gets to ride around the battlefield in an Abrams or a Bradley. Dismounted infantry, combat engineers, artillery crewmen, and truck drivers will have to suit up in a chemical environment. But today’s masks and protective suits are the best in the world. The masks are lighter, provide better vision and air circulation, and have a better seal. The suits are lighter than those in the past and have a superior protective capability. Finally, U.S. forces have better detection equipment now than in 1991. In some cases, chemical agents can be detected five kilometers away.

The best way to ensure that a chemical attack has the least effect on allied troops is to go in with the expectation that such an attack will occur. That’s what happened in 1991. And although it is easier said than done, one of the best ways for an attacker to counter a chemical attack is to keep moving. Attacking U.S. forces will be most vulnerable to chemical-weapon strikes when the momentum of the advance is slowed by the necessity of crossing an obstacle. No doubt this reality will have a great deal to say about the axes of advance for the allies.

However, when all is said and done, the greatest threat of chemical weapons is not to the advancing forces, but to fixed logistics and air bases, Kuwaiti civilians, and, of course, Israel. These are all real problems, but not showstoppers. When it comes to chemical weapons, as the old saying goes, hope for the best; prepare for the worst.

Mackubin Thomas Owens is professor of strategy and force planning at the Naval War College in Newport, RI, and an adjunct fellow of the Ashbrook Center. The views expressed here are his own and do not reflect the position of the War College, Navy Department, or Department of Defense.