WASHINGTON — THE CONTINUING furor over Iraq's chemical arsenal has left many Americans fearing that hellish poisons could rain down at any time on U.S. soldiers participating in ''Operation Desert Shield.'' In fact, the dangers posed by chemical warfare, many defense analysts say, are overstated.
Iraq indisputably does have a large stockpile of war chemicals -- thousands of tons of blistering mustard gas and hundreds of tons of the lethal nerve agents, tabun and sarin -- churned out by at least five major production and research facilities. Iraq has also amply demonstrated its willingness to use lethal chemicals. During the Gulf War, some 45,000 Iranian troops and defenseless Iraqi Kurds were killed or wounded by chemicals.
But it is not at all clear that U.S. troops confront a similar danger -- especially if they remain hunkered down in their current defensive positions in Saudi Arabia.
''The nitty-gritty question is, can [Iraq] really deliver chemical weapons against our forces,'' says Elisa D. Harris, a Brookings Institution chemical-warfare expert. ''And on that point I have serious doubts.''
For short-range battlefield attacks, Iraq can deliver chemical agents with artillery shells and multiple-rocket launchers. To lob chemicals over longer ranges, Iraq would have to rely upon aircraft. But Iraqi air forces, far less well equipped and trained than those now arrayed against them, have little chance of penetrating Saudi air space.
Nor does Iraq yet have chemical warheads for its 180-mile-range Scud-B missiles. Dispersing volatile vapors from longer-range missiles is quite a challenging technical proposition, defense experts say.
''Chemical weapons may be the 'poor man's atom bomb,''' observes Lee Feinstein, an analyst for the Arms Control Association. ''But that doesn't mean that the technology to deliver chemical weapons is available to poor men.''
U.S. ground forces would, however, be much more likely to encounter chemical warfare if they go on the offensive -- trying to push Iraq out of Kuwait, or even invading Iraq itself.
In a background interview, an expert at the U.S. Army War College's Strategic Studies Institute, who co-authored a report on Iraqi military power and U.S. security, said that Iraq generally used chemicals in its war with Iran when confronted with possible defeat.
''When they were really having trouble coping with 'human wave' attacks, their modus operandi was that they would ... drop chemicals on the logistics supply areas of the rear and that way 'starve' the invasion,'' he said.
Anthony H. Cordesman, a military-affairs aide to Sen. John McCain, R-Ariz, and author of ''The Iran-Iraq War,'' offers a similar analysis. ''As they improved their targeting capability and combined [air-ground] operations, they learned to use chemical
arms offensively,'' he says. ''They learned to use persistent agents like mustard to preserve their flanks to prevent forces massing against them.''
But there is a big difference between fighting the 24th Mechanized Infantry Division and fending off a human wave of Iranian youths with little more than kerchiefs over their faces for chemical protection.
In the Gulf War, Iraq sometimes dropped chemicals simply by kicking canisters out of aircraft; American control of the air would render such crude tactics moot in a second Gulf War. The U.S. Army also has radars that can direct devastating ''counter-battery fire'' to knock out Iraqi artillery positions.
Moreover, U.S. forces are much better trained and equipped than were Iran's to cope with Iraqi chemical attacks. ''If they can actually deliver chemical weapons, our forces are very well-protected,'' Brookings' Ms. Harris says.
Iraqi President Saddam Hussein also faces a powerful deterrent factor that didn't exist in the war with Iran. While Washington reacted with almost indifference to Iraqi chemical attacks in the Gulf War, it might well respond to such use against American forces with a massive conventional bombing campaign against Iraq. (On August 14, Defense Secretary Dick Cheney all but ruled out U.S. chemical retaliation, remarking that he could not ''conceive of a situation in which the United States would want to use chemical weapons.'')
Finally, there is little evidence that chemical weapons are sure-fire war-winners. Reportedly, shifts in the wind blew Iraqi gases back in the faces of Iraqi troops -- with deadly, unintended effects -- during at least three major battles in the 1980s. And the 45,000 reported gas casualties were only a tiny percentage of the estimated 1 million casualties of that long bloodletting.
''The use of chemical weapons against U.S. forces would impose a burden, but it is a burden that can be managed,'' concludes Matthew S. Meselson, a Harvard University biochemist and noted chemical warfare expert. ''It almost certainly would not be as big a casualty-inducing threat as explosives.''
Indeed, the toll exacted by chemical weapons seems to be psychological: something about gas warfare excites an almost primordial fear and loathing. Yet nearly a century of modern warfare, with the total dead numbering nearly 100 million, has revealed that there are many more efficient ways to kill people than with chemical weapons.
Morrison is national-security correspondent for the National Journal.