Washington has ordered Anthropic – a leading entity in America’s AI sector – to block all foreign nationals from accessing its latest models, Fable 5 and Mythos 5, citing national security concerns, according to the Silicon Valley-based firm.The unprecedented export-control measure – the first to target specific AI models – came just days after Anthropic released the models, underscoring Washington’s increasingly hands-on approach to regulating frontier artificial intelligence technologies.According to Anthropic’s statement, issued on Friday night, the directive arrived at 5.21pm Eastern time and extends even to Anthropic’s own foreign-born employees.“The net effect of this order is that we must abruptly disable Fable 5 and Mythos 5 for all our customers to ensure compliance. Access to all other Anthropic models will not be affected,” the company said.Anthropic released Fable 5 and Mythos 5 on Tuesday, marketing them as its most powerful models to date. Both systems have similar underlying technical foundations, but only Fable 5 was released to the public with additional safety and security restrictions, while Mythos 5 was released only to trusted partners.Anthropic previously warned that Fable 5 “could be misused to cause serious damage” without the safeguards it introduced, including restrictions on discussing sensitive cybersecurity, biology and chemistry topics.The releases came two months after Anthropic first unveiled a preview version of the Mythos model to a small group of industry partners under an initiative called Project Glasswing, touting unprecedented cybersecurity capabilities.