Anthropic disabled public access to its two most advanced artificial-intelligence models, Fable 5 and Mythos 5, on Friday evening after the U.S. government ordered the company to bar all foreign nationals from using them, an export-control directive Anthropic said it received at 5:21 p.m. Eastern with no detailed explanation of the security concern. Rather than try to filter users by nationality on short notice, the company pulled the models for every customer worldwide.

The order halts the commercial rollout of the most powerful systems Anthropic has ever released to the public, days after their debut, and opens a second front in the company's fight with the Trump administration over who decides when a frontier model is too dangerous to ship. Anthropic's other Claude models remain available.

What the order covers

The directive cited "national security authorities" and instructed Anthropic to suspend all access to the models "by any foreign national, whether inside or outside the United States, including foreign national Anthropic employees," CNBC reported. Foreign workers at the company in the U.S. are covered. Anthropic said the letter did not spell out the specific concern, and the company concluded only after its own review that the trigger was most likely a report on a narrow capability to have a model read a codebase and patch software flaws.

Mythos 5, the more capable system, is not generally available. The company has limited it to government agencies and a small group of corporate partners through a cybersecurity initiative called Project Glasswing, building on a Claude Mythos Preview that drew attention from Wall Street and federal officials in April for its ability to find software vulnerabilities. Fable 5, released this week, was built on the same technology with cybersecurity and biotechnology capabilities blocked, according to Al Jazeera.

The company's pushback

Anthropic said Friday it would comply but disputed the basis for the order. "We are complying with the government's legal directive and are removing access to Fable 5 and Mythos 5 for all users," the company said in a statement reported by the Washington Examiner. "However, we disagree that the finding of a narrow potential jailbreak should be cause for recalling a commercial model deployed to hundreds of millions of people. If this standard was applied across the industry, we believe it would essentially halt all new model deployments for all frontier model providers."

Anthropic described the cited capability as "asking the model to read a specific codebase and fix any software flaws." Models from rival OpenAI possess the same capability, the company told Al Jazeera.

Anthropic also signaled that it views the procedure itself as flawed. "As we have stated publicly, we believe the government should have the ability to block unsafe deployments, as part of a statutory process that is transparent, fair, clear, and grounded in technical facts," the company told CNBC. "This action does not adhere to those principles."

A second front

The export-control order is the second public clash this year between Anthropic and the federal government. After negotiations with the Pentagon collapsed earlier in 2026, the Department of Defense designated Anthropic a supply-chain risk, a label historically reserved for foreign adversaries that requires defense contractors to certify they will not use Claude in military work. Anthropic sued the Trump administration to overturn the designation, and the litigation is continuing, CNBC reported.

Counterpoint

The national-security case rests on a real capability. Al Jazeera reported that the technology behind Mythos is unusually good at finding software vulnerabilities, some undetected for decades, and that U.S. authorities and selected companies have already used it to harden their own systems. The longstanding concern, the outlet noted, is that the same tool in foreign hands could become a cyberweapon. Anthropic itself argued in a blog post this month that leading AI companies should coordinate to slow development, writing that "it would be good for the world to have the option to slow or temporarily pause" the technology's progress as it accelerates.

Whether the order survives in its current form, or is narrowed once Anthropic receives a fuller explanation of the government's concern, will determine how quickly Fable 5 returns and on what terms. The company has not given a timeline for restoring access.