Yemen cell used Claude to design guided rockets and missiles, Anthropic reveals

A cell of "malicious actors" based in northern Yemen used Claude, the artificial intelligence system built by US company Anthropic, in an attempt to develop guided weapons, the company announced Thursday, as Iran-backed Houthi rebels press a major offensive across Yemen.

"We identified a cell of threat actors based in northern Yemen running three weapons development programs," Anthropic said in a report detailing how it detects and disrupts illegal uses of Claude around the world. 

The three programs involved "a guided rocket that used a commodity phone-class flight computer with final-phase homing guidance," a multi-stage ballistic missile with a stated range goal above 2,000 kilometers (about 1,250 miles), and a missile family known as the "R2000," which included a hypersonic glide vehicle variant,  technology typically associated with only the world's most advanced militaries.

Claude used "in place of human engineers"

According to Anthropic, the group used Claude Code to carry out software engineering work that would otherwise have required a team of specialized engineers, focusing on guidance, navigation and control software for the airborne weapons. 

The company said operators assigned different instances of the model specific technical roles and attempted to conceal the true purpose of their work while doing so.

The activity took place between December 2025 and August 2026, involving Claude's Haiku, Sonnet and Opus models, before Anthropic detected and disrupted it, banning the accounts involved.

Anthropic said it found no evidence the group succeeded in fielding an operational weapon, but confirmed the cell did carry out a live field test of a guided rocket. "This field test appears to have failed," the company said. "Within hours, the actors returned to Claude to work out why it failed."

The company noted that some of the group's capabilities may persist independently of Claude, as the cell had reportedly built an offline simulation toolkit capable of running without Claude or commercial engineering software such as MATLAB.

Not explicitly named, but likely linked to the Houthis

While Anthropic's report does not explicitly identify the actors, northern Yemen — including the capital Sanaa, is largely under the control of the Iran-aligned Houthi movement, and subsequent reporting has described the cell as Houthi-linked.

The disclosure comes at a delicate moment: the Houthis have recently launched a sweeping offensive across Yemen toward the strategic Bab al-Mandeb strait, a vital corridor connecting Europe and Asia via the Suez Canal, while also escalating attacks on Saudi Arabia's oil infrastructure. 

The Yemen case was one of six conventional-weapons-related cases identified in Anthropic's broader threat intelligence report, which also documented attempts to misuse Claude for cyber-espionage and other high-risk activities.