US Government Orders Anthropic to Block Foreign Access to Its Most Advanced AI Models

The U.S. government issued an export control directive ordering Anthropic to suspend access to its two most advanced AI models, Fable 5 and Mythos 5, for all foreign nationals, citing national security concerns about a potential method of bypassing safeguards that could enable the models to identify software vulnerabilities. Anthropic complied but publicly disputed the rationale, saying it had received only verbal evidence of a narrow potential jailbreak and that applying this standard across the industry would effectively halt all new frontier model deployments globally.