Anthropic shuts down access to its most advanced AI models after U.S. government order barring foreign nationals from using them.

What happened: The U.S. Commerce Department ordered Anthropic to suspend access to its Fable 5 and Mythos 5 models by any foreign national, whether inside or outside the United States, citing national security concerns. Anthropic has since disabled access to both systems for all customers to ensure compliance.

Why it matters: This marks the first time the U.S. government has imposed such sweeping restrictions on a frontier AI model (an advanced language system that generates text) developed by an American company itself—not just on hardware exports like semiconductors or supercomputers. The measure raises constitutional and commercial concerns for AI developers and their international user base.

What to watch: The precedent set by this order may shape how the U.S. regulates AI technology going forward, particularly as other administrations have already limited access to advanced chips and computing hardware on national security grounds.