BUFFALO, N.Y. -- The United Nations announced Tuesday that clouds of chemical weapons may have been released from a second large Iraqi ammunition depot in the vicinity of American troops during the 1991 Gulf War, raising the possibility that the number of troops exposed to chemical weapons could be far larger than the Pentagon's latest estimate of as many as 100,000.
U.N. weapons inspectors said that Iraq informed them only last year that hundreds of rockets filled with mustard gas and nerve gas had been stored during the war at the depot in Ukhaydir in southern Iraq, about 185 miles north of the Saudi city of Rafha, where thousands of American troops were deployed.
The United States received this evidence earlier this year. Tuesday the Pentagon and the CIA confirmed that the Iraqi site had been bombed on Feb. 14, 1991, and that the United States now presumed that the bombing by the American-led military alliance had released a plume of chemical weapons.
They said that preliminary computer models suggested it was unlikely that the cloud had reached American troops in Saudi Arabia, although more modeling was needed before it could be ruled out.
"Obviously you don't want to end up alarming people about a situation like this," said Robert D. Walpole, who is overseeing the CIA investigation of chemical exposures during the Gulf War. He acknowledged that if all of the hundreds of rockets had been destroyed at the site, the plume of chemicals would have "come close" to American troops in Rafha, but he said that it was highly unlikely.
This is the second time in two years that the U.N. weapons inspectors have provided the Pentagon with unwelcome news about the possible exposure of American troops to chemical weapons. They are testifying here at a regional meeting of the Presidential Advisory Committee on Gulf War Veterans' Illnesses, a special investigative panel.
For more than five years after the war, the Defense Department had insisted that it had no evidence to suggest that American troops had been exposed to Iraqi chemical weapons -- and no answers for the thousands of veterans who had complained of mysterious health problems.
Last year, however, the Pentagon reversed itself and announced that it had received evidence from the United Nations suggesting that American troops had been exposed to a cloud of the nerve gas sarin when they blew up a sprawling Iraqi depot in the southern Iraqi village of Kamisiyah, in March 1991, shortly after the war.
Initially, the Pentagon suggested that only a few hundred American soldiers might have been exposed to chemical weapons released from Kamisiyah. But the estimate has grown repeatedly over the last year and last week the Pentagon announced that its latest computer models showed that the plume of nerve gas had passed over as many as 98,900 American troops, or about 1 out of every 7 American soldiers who served in the war. Saudi and Iraqi civilians may have been contaminated as well.
James Turner, the chief investigator for the White House panel, said that Tuesday's announcement on Ukhaydir was "obviously a significant development" given the possibility that many more troops were exposed to chemical weapons than previously thought.
"We need to do modeling to determine whether there was any U.S. downwind hazard from that bombing," he said.
The committee, which includes scientists and physicians, was created by President Clinton in 1995 to investigate the ailments being reported by thousands of Gulf War veterans. More than 100,000 veterans have sought special medical checkups from the Defense Department and the Department of Veterans Affairs.
In a report last January, the committee said that chemical weapons were probably not responsible for the veterans' health problems, although it called for millions of dollars in new research on the health effects of exposure to low levels of chemical weapons.
Scientists are divided on the question of whether trace levels of nerve gas and other chemical weapons could produce the health problems found among the veterans.
Charles Duelfer of the U.N. Special Commission on Iraq, which conducts the international arms inspections imposed on the Iraqi military after the war, said Tuesday that the Iraqis came forward only belatedly with information about the storage of chemical weapons at Ukhaydir.
He said that while chemical weapons had been stored at Ukhaydir during the war, but moved elsewhere afterward. This apparently convinced the Iraqis initially that they were not responsible for declaring it as a chemical storage site.
"They had said that because there were no weapons at the time when we were initially conducting our investigations, they assumed it was not of interest to us," Duelfer said.
He said a team of U.N. arms inspectors visited Ukhaydir for the first time last April and found damaged 155-millimeter rocket shells that may have once contained mustard gas. "There were also bomb craters there," he said. "It's logical that the Iraqis didn't bomb themselves."
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