Anthropic’s September 2026 Threat Intelligence report (Detecting and countering misuse of AI; activity December 2025–August 2026) details a northern Yemen weapons-development cell running three programs: a guided rocket using a commodity phone-class flight computer with final-phase homing; a multi-stage ballistic missile with a stated range goal above 2,000 km; and a multi-variant “R2000” set including a hypersonic glide vehicle variant. Actors used Claude Code in place of human software engineers for guidance, navigation and control (GNC) — integrating open-source autopilot onto phone-class flight computers, writing control/position-estimation software, tuning settings, running firmware builds and simulations — and ran multiple Claude instances in parallel roles (code, research, review).

Safeguards blocked many requests; actors hid goals/products and split work across sessions. Anthropic does not have evidence they fielded an operational device, but they did test-fire a guided rocket that appears to have failed (they returned to Claude within hours to diagnose). Accounts banned; threat info shared with partners. Actors had already built an offline simulation toolkit that does not rely on Claude or MATLAB.

Anthropic tracks the cell as GTG-87001. (source: Anthropic TI)

Correction (30 Oct 2026): removed a statement that only SecurityWeek, which this desk cannot read, gave, so the card now rests on Anthropic's report; the card date also moved from 11 to 10 September 2026, the date Anthropic's Threat Intelligence page gives the September 2026 report, and the card now gives the report's tracking name for the cell. (source: Anthropic)