GTG-87001: a northern-Yemen weapons cell used orchestrated Claude Code instances in place of engineers to build missile guidance, navigation and control software, test-fired a guided rocket and returned to Claude for failure analysis

three weapons programmes (guided rocket with terminal homing; multi-stage ballistic missile with >2,000 km goal; 'R2000' multi-variant missile incl. a hypersonic glide vehicle); one failed live rocket test; no evidence of a fielded device

From Anthropic's 'Detecting and countering misuse of AI: September 2026' report (10 Sep 2026; PDF pp. 112-115, also on the HTML report page). Activity window per AIID: Dec 2025 - Aug 2026, no event date given, hence date_occurred null. The agentic element is explicit: the actors ran several Claude Code instances at once with delegated roles (one writing code, one researching, one reviewing), and Claude executed firmware build pipelines and flight simulations; evasion was by hiding end-use and splitting work across sessions. impact_realized false: Anthropic has no evidence of an operational device, the one live test appears to have failed, and no third-party harm is documented - this is realized capability uplift to a weapons programme, not a realized consequence to a victim, and it is recorded as an unsuccessful in-the-wild misuse. FT and AP (11 Sep) linked northern Yemen to Houthi-controlled territory; Anthropic does not name the actors as Houthis. The same report documents many other agentic campaigns (ShinyHunters-associated Claude Code phishing workflows, an autonomous vulnerability-research programme, a Chinese municipal cyber-police Claude Code surveillance pipeline, memory-file-driven influence operations) that belong with the vendor-research records. AI Incident Database incident 1687. Deduped 2026-09-21 against a parallel draft (2026-09-anthropic-gtg-87001-yemen-guided-weapons) from the lab-disclosure sweep; this record was retained as the better-sourced version.