The US government ordered Anthropic to pull the plug on two of its most advanced AI models. Three days after launch.
On June 12, 2026, a federal export control directive mandated the immediate suspension of access to Anthropic’s Fable 5 and Mythos 5 models for all foreign nationals, including the company’s own employees. The reason: a narrow jailbreak vulnerability that officials say could lead to the exploitation of security weaknesses. Anthropic complied, shutting down access across the board.
Three days from launch to lockdown
Fable 5 and Mythos 5 had been released on June 9, 2026. The government intervened 72 hours later, making this one of the fastest regulatory clampdowns on a major AI product in recent memory.
Mythos itself wasn’t exactly new to the scene. Anthropic had first previewed the model in April 2026, positioning it as a cybersecurity tool designed to identify software vulnerabilities in critical infrastructure. Anthropic initially released it to a small group of partners exclusively under Project Glasswing for defensive cybersecurity purposes before expanding its offerings.
