James Taylor of Pacheco can't say just what turned him from an ultra-fit Marine combat swim instructor to a disabled asthmatic with chronic bronchitis whose severe attacks prompt frequent scrambles to the emergency room.

Whatever it was, Taylor traces it to the Persian Gulf, where he served before returning home in 1991 with breathing problems and horrible coughing fits.

"When we got there we didn't have biological equipment. We had second-rate gas masks, no chem or bio suits," said Taylor, now 35. "You throw that in with botulism shots, pills for nerve agents and blood agents, anthrax ... I'm not a scientist. I can't say for sure."

Like many veterans who have been denied a recognized link between their unexplained symptoms and service in the Persian Gulf, Taylor wonders if U.S. military leaders will take the war's lessons to heart as the Bush administration readies a new attack on Iraq.

Pentagon officials say they have. Missteps during the gulf war have prompted a renewed focus on soldier health, as military leaders contemplate a new kind of warfare, and an Iraqi government armed with untold chemical and biological weapons.

Among the lapses of 11 years ago, federal officials acknowledge inadequate protective gear, excessive false readings from chemical sensors, mismanagement of medical records and poor administration of a stew of vaccines and inoculations.

Vaccine shortages left many soldiers without, while others took far too much. Some received the anthrax vaccine without knowing. Who and how many is unknown because of bad record-keeping.

"We didn't know what we were going up against," Taylor said. "They really don't have an excuse this time."

Concerns from the gulf war drove the Pentagon to launch a major "Force Health Protection" initiative to safeguard soldiers. Congress in 1997 weighed in with a law demanding that soldiers undergo health screenings before, during and after they deploy.

The Defense Department now has better gas masks and protective suits, decontamination units and chemical detection equipment, and the services have developed better training to prevent chemical, biological and radiation exposure.

Yet problems persist.

The General Accounting Office, while acknowledging advances since the gulf war, recently found that the Pentagon lost track of as many as 250,000 defective chemical-warfare suits and that defense officials have no solid strategy for low-level exposures to chemical agents.

Medical panels and a presidential committee on gulf war illnesses recommended several measures to protect the health of soldiers. But a report two years ago by the Institute of Medicine found the response lacking.

"The most important recommendations remain unimplemented despite the compelling rationale for urgent action," the report found.

A major problem is tracking soldier movement and maintaining health records that can be accessible to military and private doctors when soldiers return home. Earlier this year, the Department of Defense created a new directorate to oversee those efforts.

"We've made some good strides, but we really need to do a much better job of keeping medical records, making sure vaccinations are given before we get into theater," said Dr. Michael Kilpatrick, deputy director of the Defense Department's Deployment Health Support Directorate.

Kilpatrick said the Pentagon now sends advance teams to sample air, water and ground before operations move into an area. In Afghanistan, Special Forces use Palm Pilots to keep medical records, he said. During the gulf war, many paper records disappeared.

Gulf war veterans groups remain skeptical. They have spent years fighting for health care, battling the Pentagon for information and demanding recognition and funding of research that seeks to explain why some soldiers fell ill, while others who fought alongside them remained healthy.

Gulf war veterans are divided over a new foray into Iraq, said Steve Robinson, executive director of the National Gulf War Resource Center.

"Those who aren't sick say 'Let's go back and finish the job,'" said Robinson, a former Army Ranger. "If they know someone who is sick or are sick themselves, they are very leery of going back to fight what will certainly be a chemical and biological war."

The federal government has spent more than $120 million studying possible causes of the mysterious conditions reported by gulf war veterans, including fatigue, muscle pain, memory loss, sleep disorders, respiratory trouble and other chronic illnesses.

Gulf war veterans complain of symptoms at more than twice the rate as those who did not serve there, defense officials say.

But they have reported only one scientific link -- a recent finding that veterans who served in the Persian Gulf region are at greater risk for amyotrophic lateral sclerosis, or Lou Gehrig's disease, a rare and fatal neurological illness. The reason is unclear.

On Oct. 31, the Department of Veterans' Affairs said it would more than double research funding for gulf war illnesses. The announcement came after a British study, funded by the U.S. Department of Defense, found that gulf war illnesses were not stress-related psychiatric disorders.

Some research points to neurological damage.

An advisory committee in June estimated that between 25 percent and 30 percent of the 700,000 U.S. veterans who served in the gulf war are now ill.

More than 8,000 have died. By comparison, 148 troops were killed in action, and fewer than 500 were wounded in the Persian Gulf region during the war.

"It was the anti-Vietnam War. It was the clean victory. The problem was, you could be injured from more than bullets and bombs," said Robinson. "Science is just now catching up."

Veterans point to a host of possible causes for their illnesses.

Among them are smoke from oil fires set by the Iraqis; depleted uranium used in U.S. ammunition; vaccines and inoculations, including an anthrax vaccine and an experimental botulism vaccine; and sarin nerve gas exposure from the destruction of weapons at an Iraqi munitions depot.

"To have so many possibilities on the table is just medically not a tenable situation," Kilpatrick said. "We need to have that baseline information, to say what we can rule out, even if we're not able to diagnose a disease and recognize symptoms."

More difficult, he said, is changing a culture in which military planning trumps health care. "The biggest obstacle clearly is the demands of the battlefield. We have to find a happy medium."

The task is more urgent, with Iraqi leader Saddam Hussein's apparent readiness to deploy chemical or biological agents in battle, regardless of the impact on his own fighters, said Rep. Christopher Shays, R-Conn., chairman of the House Subcommittee on National Security, Veterans Affairs and International Relations.

Shays, who led congressional hearings on gulf war illnesses, has criticized the Pentagon's insistence that hazardous exposure levels were not enough to sicken the troops.

"The military's the military. When they go into battle, they don't always keep the best medical records and so on," he said. "But there's no illusion about the environment we're sending our soldiers in. Battlefields are always toxic. In this case, beyond toxic, you may have chemical and biological agents."

One of the biggest problems during the gulf war were false alarms from tightly calibrated chemical sensors. Soldiers didn't know what was real, said Dr. Bernard Rostker, the Pentagon's top official for gulf war illnesses during the Clinton administration.

"They were basically useless," said Rostker of the sensors. "There are new sets of alarms, much more sensitive."

Rostker, who said he spent four years "trying the damnedest to pin (gulf war veterans' illnesses) to something," said the changes hold promise.

"We're better prepared than we were, and we're much more sensitive to the fact, 'Pay me now or pay me later,'" Rostker said. "Whether you learn enough, God knows. I hope we don't have to prove it."