GAO/NSIAD-92-340 found 'strong evidence' supported a Patriot warhead kill in only about 9% of the engagements the Army claimed as kills

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The U.S. General Accounting Office's September 1992 report, Operation Desert Storm: Data Does Not Exist to Conclusively Say How Well Patriot Performed (GAO/NSIAD-92-340), reviewed the Army's Gulf War claims that Patriot interceptors had destroyed Scud missile warheads and applied its own evidentiary standard rather than accepting the Army's tally. GAO's own abstract states: "strong evidence exists for about 9 percent of the engagements that the Army believes resulted in warhead kills, including a ground damage report that a Scud had been recovered with Patriot fragments or fragment holes and radar tracking evidence that the Scud experienced a dramatic slowdown and that debris was present after a Patriot intercept."

This is the strictest published estimate of Patriot's actual warhead-kill rate in the 1991 Gulf War — well below the Army's own revised claim of 52%, only 40% of which it graded "highest confidence" (see claim-patriot-army-effectiveness-claim-collapsed-from-96-to-52-percent). It sits alongside the independent video-evidence finding of no unambiguous Scud warhead kill at all (claim-lewis-postol-1993-no-video-evidence-of-patriot-scud-warhead-kill) as a second, differently-sourced line of evidence converging on the same conclusion: the wartime success narrative did not survive review. The definitional split behind this 9% figure — what counted as "strong" versus weaker evidence — is treated separately in claim-gao-nsiad-92-340-two-tier-strong-vs-lesser-evidence.