Spc. Alan Davidson and Pfc. Kevin Hayles were smoking cigarettes in the swirling dust outside their tent when soldiers in a nearby motor pool suddenly donned their gas masks.
Five seconds later, theirs were on, too. They ran back to their tent to warn the men in their unit to pull on their masks as well.
During a lunchtime drill Tuesday, soldiers across Camp Udairi took shelter in sandbagged bunkers, dove under 5-ton trucks and hit the ground, another round of practice for a common nightmare: a chemically loaded Scud missile attack by Iraqi forces.
"Everybody's really quick about it because they know at anytime it might not be a drill," said Davidson, 24, of Port Charlotte. He and Hayles work on helicopters for the 8th Battalion, 101st Aviation Regiment of the 101st Airborne Division.
"Everybody's afraid of a biological or chemical attack that could screw you up for the rest of your life," Hayles, 25, added.
"Or end it," Davis interjected. "We're all trained to handle it, but you never really know."
Officers and sergeants assigned to prepare their units for nuclear, biological and chemical attack _ known as NBC _ say they have faith in the gas masks, protective suits and detection devices designed to safeguard U.S. troops.
But almost without exception, American soldiers at desert posts along the Iraqi border say they fear chemical or biological weapons far more than Iraqi bullets, artillery or even mines. And unlike with conventional weapons, those at the rear are at as much risk of being gassed as those at the front, if not more.
"With a bullet they can do surgery and pull it out and stitch you back up," said Pvt. Garland Anderson, 22, of Richmond, Va., a computer networker with the 101st Airborne. "With NBC, they scrub you down and hope they got all of it."
The soldiers' list of fears runs long:
They won't know they've been hit until too late.
Their masks and hooded rubberized suits won't work well enough, or they won't get the suits on in time.
And even if they survive an attack and seem uninjured, they will suffer health problems for years to come. One sergeant related how his grandfather survived a mustard gas attack during World War I, but died of complications at 43.
"If I'm going to die, I'd rather be shot quick," said Pfc. Derek Vasquez, 18, of Buffalo, N.Y., a rifleman in the 3rd Battalion, 502nd Infantry. "Who wants to be nuked? Who wants to be chemically burned?"
Vasquez said he feels as prepared as possible and has faith in his training, but he believes surviving an attack ultimately will depend on the soldier and the conditions.
"If you've got headphones on or you're not really paying attention, if you're near a generator or something and you can't hear "gas, gas, gas,' " a soldier may not react in time, he said.
The Army is trying to combat these fears and protect its troops with frequent training, good equipment and high-tech, early warning devices.
At the camps along the Iraqi border _ Udairi, Pennsylvania, New York, New Jersey, Virginia and Victory _ the gas mask is given the same priority as the gun. Repeatedly, soldiers practice donning it in nine seconds or less, the Army standard. Men keep clean-shaven so facial hair won't interfere with the seal between their skin and the rubber mask.
"You will carry your mask indefinitely," Sgt. 1st Class Daniel White, the NBC coordinator for the Airborne's Division Support Command, told his soldiers during a recent training session.
"The only time you take it off is when you're showering or when you're sleeping, and then it will be within arm's reach."
All soldiers, except those with medical exemptions, have been vaccinated against smallpox and anthrax. Meanwhile, several mobile biologic detection units are stationed at each U.S. camp in Kuwait and will join soldiers in the field if the United States attacks.
Each unit is essentially a small lab on the back of a Humvee, where technicians test the air for anthrax, smallpox and other biological dangers.
The Army also has six-wheeled vehicles called the Fox, which look somewhat like an armored personnel carrier. The Fox roams the desert and accompanies convoys, sniffing for nerve gas and other chemical agents.
The Fox crews also can take air and soil samples, and find routes around contaminated areas.
Most units travel with portable detection devices that work somewhat like smoke alarms: If they detect the presence of nerve or blister agents, they scream.
U.S. military planners do have cause for worry. The Iraqi army has used chemical weapons with deadly effect, including during the Iran-Iraq war and against the Kurds in northern Iraq.
The United States contends Iraq still has supplies of blister and nerve agents, which Iraq denies. The existence of these weapons of mass destruction are at the center of the dispute between the two countries, and United Nations inspectors began searching Iraq for evidence last fall.
Staff Sgt. Truck Carlson, a mental health counselor at the 86th Combat Support Hospital at Camp Udairi, said almost one-third of soldiers who seek treatment are stressed over the prospect of chemical and biological weapons.
He tries to ease their concerns by explaining that the desert is an inhospitable environment for chemical and biological agents: The winds should blow them away, while the heat and sun quickly break them down.
Carlson also reminds them the only Iraqi weapon capable of delivering gas is a Scud missile, because Saddam Hussein has no air force. Each U.S. base has Patriot missile batteries that exist solely to shoot down incoming Scuds.
Many of his patients are senior noncommissioned officers who aren't comfortable with the NBC equipment, but don't want their young troops to sense their fears.
"Until you've done it, there's always that fear in the back of their mind: Will this (equipment) really work?" Carlson said.
At the same time, medics and NBC officers aren't stingy with the worrisome truth about chemical weapons, especially Vx, a nerve gas U.S. officials say Hussein has.
During a recent training session on how to use the Vx antidote issued to each soldier, Airborne soldiers were told how nerve gas works: It disrupts the central nervous system, and mind loses control of body. Eventually the lungs fill with fluid.
Even to career veterans such as Sgt. Maj. Lenton Vining, the command sergeant-major of the Airborne's Division Support Command, its largest brigade, the prospect is troubling.
"You can protect yourself from a bullet. NBC, no," Vining said. "All you can do is prepare for it. And that bullet takes out one person. NBC takes out a lot."