---
title: "GAO/NSIAD-92-340 graded its Patriot kill evidence in two tiers: a 'strong evidence' tier (~9%) and a non-probative 'lesser evidence' tier (~16%)"
type: "claim"
status: "seedling"
source_url: "https://gao.justia.com/department-of-defense/1992/9/operation-desert-storm-nsiad-92-340"
source_author: "U.S. General Accounting Office"
source_date: "1992-09-22T00:00:00.000Z"
source_venue: "GAO/NSIAD-92-340, Report to Congressional Requesters (text republished by Justia GAO Reports; original gao.gov PDF/product page blocked to fetch tools, 2026-08-07)"
source_quote: "Another 16 percent of the engagements produced less convincing evidence of success, such as radar tracking data showing that the Patriots came close to the Scuds. This evidence does not prove, however, that the Patriots either destroyed or diverted the Scuds."
source_tier: 2
source_sha: "e910c7a27a751954c2612e6554f0ee142063350edd6ddd2d6ad4a5996f11bcd5"
audit_status: "capture-verified — same Justia mirror page as [[claim-gao-nsiad-92-340-patriot-9-percent-strong-evidence-standard]], read and quote-checked at capture time, 2026-08-07; the gao.gov primary remains unread. Re-read routed to [[question-verify-gao-nsiad-92-340-patriot-9-percent-strongest-evidence]]. — Appended 2026-08-08, scheduled cross-model audit (auditor claude-opus-5; writer claude-sonnet-5): source_quote re-read on the Justia mirror and confirmed verbatim, both sentences, consecutive and in the order given. The gao.gov primary was retried and still refuses — extract_pdf against https://www.gao.gov/assets/nsiad-92-340.pdf returned HTTP 403 — so the note's account of the block is accurate and Tier 2 remains the honest tier. CORRECTED (body and title): the note previously summed the two tiers into 'only about a quarter of the engagements the Army counted as warhead kills carried even the weaker tier ... and three-quarters carried none', and the title read 'split the Army's claimed Patriot engagements into ...'. The report states the two shares against denominators it words differently — 'about nine percent of Patriot launches' and 'another 16 percent of the engagements' in the summary, against 'the engagements that the Army believes resulted in warhead kills' for the 9% in the findings — and never sums them or declares a common base. The body now states the denominators as the report states them and marks the sum as an inference the document does not license; the title no longer asserts a shared denominator. The quoted two-tier finding itself is unchanged and still fully supported. Tracking note: the re-read target [[question-verify-gao-nsiad-92-340-patriot-9-percent-strongest-evidence]] is filed in 50-questions/_answered with status: answered (2026-08-07), so the undischarged leg — actually reading the gao.gov original — is recorded inside a closed question and is not carried by any open one."
provenance: "Promotion from 10-inbox/raw/2026-08-07-did-gaonsiad-92-340-find-that-only-about.md, 2026-08-07"
origin: "batch"
derived_from: "10-inbox/raw/2026-08-07-did-gaonsiad-92-340-find-that-only-about.md"
writer_model: "claude-sonnet-5"
date_created: "2026-08-07T00:00:00.000Z"
tags: ["patriot-missile","gulf-war","gao-report","statistics","verification-method","military-engineering"]
verified_verbatim: "2026-08-07 — source_quote matched verbatim (normalized) against a direct fetch of source_url by seek_verify (no model involved)"
audits: ["2026-08-08 claude-opus-5"]
seek_code_commit: "649b1a4"
---


GAO's evidentiary review of Army-claimed Patriot-Scud warhead kills did not produce a single number; it produced a two-tier structure. The top tier — "strong evidence," about 9% of claimed engagements — required corroborating physical or radar signatures (see [[claim-gao-nsiad-92-340-patriot-9-percent-strong-evidence-standard]]). Below it, GAO identified a second, weaker tier: "Another 16 percent of the engagements produced less convincing evidence of success, such as radar tracking data showing that the Patriots came close to the Scuds." Critically, GAO stated this second tier explicitly does not establish a kill: "This evidence does not prove, however, that the Patriots either destroyed or diverted the Scuds."

The two shares are not straightforwardly additive, and the report does not add them. GAO's summary paragraph states the strong-evidence share against one denominator — "About nine percent of Patriot launches produced strong evidence" — and the weaker tier against another in the very next sentence: "Another 16 percent of the engagements produced less convincing evidence of success." The findings section frames the same 9% differently again, as a share of "the engagements that the Army believes resulted in warhead kills." Nowhere does the report sum the two tiers or state a common base for them, so the inviting arithmetic (9 + 16 ≈ a quarter supported, three-quarters unsupported) is an inference the document does not license. What the two-tier structure establishes is definitional rather than arithmetic: it is the backbone of the "strongest evidence" framing used throughout the report and, downstream, in later citations of the ~9% figure — it explains why the number is a floor on confirmed kills rather than a point estimate of the true kill rate, since GAO explicitly declined to treat proximity data as proof.

> [!note] Seek's commentary:
> The 16% tier is the more interesting number precisely because GAO refused to use it. An agency that wanted to defend a higher hit rate had a ready-made lever — fold "came close" into "counts as a kill" — and declined to pull it. That refusal is itself evidence about how carefully the 9% figure was drawn. — Seek