ON Feb. 15, 1991, near the end of the Gulf war, President Bush traveled to the Raytheon Company plant in Andover, Mass., where the Patriot missile was manufactured, and declared confidently: "Forty-two Scuds engaged, 41 intercepted!"
That claim has not stood the test of time.
In the intervening 19 months, both Raytheon and the United States Army have substantially downgraded their claims of how well the Patriot missile system performed.
The latest Army estimate, released in April, holds that 158 Patriots fired during the war destroyed roughly 70 percent of their Scud targets in Saudi Arabia and about 40 percent in Israel.
But even those estimates may be too high.
The House Government Operations Committee staff is preparing to issue a report, probably in the next week, concluding that the Army's evidence is "very weak" in most cases, a knowledgeable source says.
The committee's staff has been examining the Army study with the aid of the General Accounting Office and the Congressional Research Service. Summarizing their conclusions, the source says: "Is there evidence to support the 70 percent claim? No. If not, then what does the evidence support? Few, if any, hits."
That startling conclusion is adamantly denied by both the Army and Raytheon, which stick by their claim that the Patriot was successful in thwarting Saddam Hussein's ballistic-missile campaign against Saudi Arabia and Israel.
"Patriot's very credible performance and success can be measured by the events as they occurred. The coalition did not falter. Israel did not have to mount offensive actions against Iraq, and was able to stay out of the war. Widespread loss of civilian life was not inflicted," Robert Stein, a top Raytheon manager, wrote to military experts.
The debate over the performance of the Patriot is of more than academic interest. The multibillion-dollar weapons system is "very, very important" to the financial fortunes of Raytheon, the nation's fifth-largest defense contractor, company spokesman Pat Coulter says.
The Patriot's performance also has become entangled in the discussion over the Strategic Defense Initiative (SDI). Although the Patriot was not developed through SDI, both opponents and proponents of "Star Wars" have used the missile as fodder for their arguments over whether ballistic-missile defense is possible.
"This is a complex and controversial issue. Many lives and billions of dollars are at stake," Rep. John Conyers (D) of Michigan, chairman of the Government Operations Committee, said in April. "If American soldiers think that they can depend on Patriot battalions destroying 9 out of 10 enemy missiles, when the actual defense capability may be closer to 1 out of 50, it would be a disaster."
The forthcoming report from Representative Conyer's committee appears to vindicate the findings of Theodore Postol, a professor of science, technology, and national-security policy at the Massachusetts Institute of Technology (MIT). It was Dr. Postol who first raised substantive questions about the Patriot's performance.
Ever since the Gulf war, the nuclear physicist and former Pentagon weapons consultant has studied television footage of the Patriot in action. In all, Postol and an MIT colleague, George Lewis, say they have studied videotapes of 22 or 23 out of the 47 Patriot-Scud engagements.
"We have found no convincing evidence in the video that any Scud warhead was destroyed by a Patriot," say the two professors in a private letter to the Government Operations Committee that was obtained by the Monitor.
"We have strong evidence that Patriots hit Scuds on two occasions, but in both cases the videos also show that the Scud warheads fell to the ground and exploded," Postol and Dr. Lewis write. "These clips provide strong evidence that even when Patriots could hit Scuds they were still not able to destroy Scud warheads."
In response, supporters of the Patriot have argued that any missile interceptions by the system - which was originally designed as a defense against aircraft - is reason enough to call the Patriot a success. But they also have called Postol's evidence into question.
"It's impossible to study the endgame of a Patriot-Scud engagement that occurred at 3,000 miles per hour" using commercially available video cameras, says Peter Zimmerman, a fellow at the Center for Strategic and International Studies in Washington, D.C., who has cooperated with Raytheon. Postol replies that, in most cases, the Patriots missed their targets by such large distances - a median of 600 meters - that the misses cannot be explained by the imperfections of commercial videotape.
In any case, the Army apparently does not have any scientific evidence about Patriot-Scud engagements, either. No data recorders were installed on Patriot batteries used in the Gulf war; and US soldiers did not take any high-quality film of the Patriot engagements.
Lacking such evidence, the Army has relied on ground-damage surveys, eyewitness testimony, and other supporting data for its claims about the Patriot's success. After its initial studies were challenged by Postol and Congressional investigators, the Army mounted what one general described as a "Herculean effort" to find out the truth about the missile's performance.
"What we presented to the [Government Operations] Committee goes beyond circumstantial evidence," says Maj. Peter Keating, an Army spokesman. "We went back to look at all the raw data about every shot of the war."
But the Army's study has not impressed experts who have studied it - even those who are in favor of the Patriot program.
"I think you can make a common-sense case that Patriot was modestly successful in defending Israel," Mr. Zimmerman says, because Scuds fired at Israel did not cause as much damage as might have been expected, based on the Scuds' track record.
But he adds, "the ground-damage survey in Saudi Arabia was incompletely done, so that a similar quantitative argument probably should not be attempted."
Postol, who despite his criticism of the Patriot does not advocate its cancellation, goes further. "The evidence points to the fact that the system just didn't work," he says. But he says he is modestly optimistic about a recent Patriot upgrade.