Chem. The grunts have shortened the name of Saddam’s silent killer to a single syllable. After months of drills, they can “mask up” in as little as four seconds, then leap into protective suits, gloves and boots. They pack syringes of atropine citrate and oximes - antidotes to nerve and mustard gas. Still they are terrified. “You cannot see it, you cannot feel it, it is going to kill you,” said a tank sergeant on the Saudi border last week. “That is the evil mystique.”

Saddam had ordered his commanders to fire chemical munitions as soon as the allies launched a ground offensive, according to U.S. intelligence sources. The U.S. Central Command also believes that chemical-rocket units were moved from Kuwait City to positions near the Saudi border. Iraqi Frog-7 missiles can carry chemical warheads up to 43.5 miles; mortar and artillery pieces can deliver the same chemical agents up to 18 miles. The Iraqis might hit frontline troops with Sarin or Tabun nerve agents that dissipate quickly from the battlefield, minimizing the threat to their own troops. Soldiers manning artillery batteries, command centers and supply dumps in the rear may face mustard gas or advanced VX nerve agents that can linger for days or weeks, depending on weather conditions.

Are the allies ready? Misgivings by the brass at the start of the gulf operation gave way to guarded optimism as Desert Storm moved toward a climax. Pentagon planners believe the GIs’ masks, suits and antidotes will protect them. They also hope to keep the Iraqis confused about where to find allied troop concentrations. Central Command expects few casualties from chemical attacks; during the Iran-Iraq War just 5 percent of the soldiers exposed to chemical agents died, even though they had inferior protective gear. “Chemical weapons have been outclassed by technology and I think the war will prove it,” said Sgt. l/c Woody Davis, an officer with the First Armored Division on the Saudi border.

Still, the high-tech defensive gear weighs on the troops. Iraq developed its chemical-warfare tactics partly as a means to disrupt enemy artillery batteries and command centers. Soldiers move more slowly and fight less effectively in gas masks and heavy suits. Some might panic. After an attack, allied units would eventually need to halt their operations to be decontaminated - a huge task. A U.S. Army division, for example, needs more than 200,000 gallons of water a day to wash down from a chemical attack. Soldiers who inject themselves with atropine to survive a nerve-gas attack need a week to recover from the drug’s side effects. Allied units may try to maneuver around some gas attacks, which would add to the time needed for military objectives. But that may be a small price to pay if Saddam unleashes his most dreaded weapon.