A weapons engineering cell in northern Yemen used Anthropic's Claude Code as a substitute for human software engineers to develop guidance, navigation and control software for rockets and ballistic missiles, according to Anthropic's own threat intelligence report published on 10 September 2026.
The report, titled Detecting and countering misuse of AI: September 2026, documents activity disrupted between December 2025 and August 2026. Anthropic did not name the Houthis directly, but described identifying a cell based in northern Yemen running three weapons programmes territory the Associated Press and Financial Times link to the Iranian-backed Houthi movement.
The three programmes included a guided rocket with a phone-class flight computer, a multi-stage ballistic missile with a stated range goal of more than 2,000 km, and a multi-variant missile family called the R2000, which included a proposed hypersonic glide vehicle variant.
The cell ran multiple Claude instances simultaneously, assigning one to write code, another to research, and a third to review results. Anthropic said the actors evaded safety filters by concealing the purpose of individual tasks and splitting work across separate sessions, so no single prompt revealed the full project.
The cell test-fired a guided rocket that appears to have failed. Within hours, the actors returned to Claude to diagnose why. Anthropic said it found no evidence of a successfully fielded operational weapon.
However, before their accounts were banned, the group had already compiled an offline simulation toolkit that required neither Claude nor specialist software such as MATLAB. Once transferred to a local environment, that capability persisted beyond Anthropic's reach.
Anthropic banned the associated accounts and shared intelligence with public- and private-sector partners. The company said the case illustrated the difficulty of preventing AI-assisted weapons development when users deliberately fragment complex projects across sessions to avoid detection.
Source : Anthropic
