Claude Code used in place of human software engineers on a missile programme. (Image Credits: EYEPRESS)
Claude was used to write the software that steers and stabilises a flying vehicle
The group was working on a guided rocket, a multi-stage ballistic missile with a stated range goal above 2,000km, and a multi-variant missile set called the R2000, which included a hypersonic glide vehicle. The Yemen case is one of six conventional weapons operations detailed in the report, which covers activity Anthropic disrupted between December 2025 and August 2026. Because the actors came back to Claude within hours to work out why, bringing post-test telemetry in for diagnosis, the company knows this.
The actors hid their goals and concealed what the software was meant for, then split tasks across many sessions so no single one revealed the full programme.
Anthropic says it has shut down a cell of threat actors based in northern Yemen that used Claude to build guidance software for three weapons programmes running in parallel. In its September threat report on detecting and countering misuse of AI, the company says the actors used Claude Code in place of human software engineers. Anthropic says it has no evidence the cell managed to field an operational device.
The AI model’s job was guidance, navigation and control. In one instance the actors used Claude to integrate an open-source autopilot onto a phone-class flight computer, the sort of commodity hardware found in consumer devices. Claude wrote the control and position estimation software, tuned the control settings, ran the firmware build pipeline and performed a flight simulation. Anthropic’s safeguards blocked many of the requests. Not all of them. It did test-fire a guided rocket, and that field test appears to have failed. Anthropic banned every account it could link to the cell and shared threat information with public and private sector partners. The complication is what the group had already finished. That part of the work can continue with no platform access at all. Here, the software was visible while it was still being written.
Before the ban, it compiled a simulation toolkit into a standalone executable, a digital model of the weapons system that runs without Claude and without engineering environments such as MATLAB. The company notes that this kind of programme has historically been pieced together by governments and United Nations panels from recovered hardware, long after the fact.