Anthropic Blocks Yemen Cell Using Claude Code for Missile Software

Anthropic says it disrupted a weapons engineering cell in northern Yemen that used Claude Code to develop guidance software for rockets and missiles, according to a company report. The company found no evidence that the group fielded an operational device, although it test fired a guided rocket that appeared to fail.

The cell worked on a guided rocket with final phase homing, a multistage ballistic missile with a stated range goal above 2,000 kilometers, and a missile family Anthropic refers to as the R2000 set, which included a hypersonic glide vehicle variant. It ran several Claude instances at once and gave each one a role, tasking one with writing code, another with research and a third with reviewing the first instance's output.

Claude helped integrate an open source autopilot with a phone class flight computer, write control and position estimation software, tune settings, build firmware, and run flight simulations. After the rocket test, the actors returned to Claude within hours to work out why it had failed.

Anthropic says its safeguards blocked many of the cell's requests but not all of them. The actors hid their goals and the products the software was meant for, and split their work across multiple sessions so that no single session revealed their full intent.

Anthropic banned accounts associated with the actors and shared threat information with public and private sector partners. The cell had already built an offline simulation toolkit that runs without Claude or engineering environments such as MATLAB.

The report describes the group only as a cell of threat actors based in northern Yemen, tracked as GTG-87001, and does not attribute it to any named group. Wire coverage of the report identified the territory as Houthi controlled.