Anthropic announced on Friday that it has disabled access to its Fable 5 and Mythos 5 artificial intelligence models following a United States government export control directive issued on national security grounds.

The company said it received the order at 5:21 p.m. ET, directing it to halt access to the models for all foreign nationals, both within and outside the United States, including Anthropic employees who are not U.S. citizens.

To comply with the directive, Anthropic immediately suspended access to the affected models for all customers.

The company, however, noted that the restrictions apply only to Fable 5 and Mythos 5, with its other AI models remaining available and unaffected.

The suspension comes only days after Anthropic unveiled Fable 5 and Mythos 5, two advanced AI models the company said achieved state-of-the-art performance across several industry benchmarks.

Fable 5 was particularly notable because it marked the first time Anthropic made a model of that capability publicly available, supported by new safeguards designed to prevent responses in certain high-risk areas.

The new models build on the earlier release of Claude Mythos Preview, which drew significant attention from both government officials and Wall Street investors in April for its sophisticated cybersecurity capabilities.

While Anthropic had said it did not intend to make Claude Mythos Preview broadly available, the company has instead limited access to a select group of organizations through Project Glasswing, a cybersecurity-focused initiative.

In its statement on Friday, Anthropic said U.S. authorities did not disclose the specific national security concerns behind the export control order. The company apologized for the disruption caused by the sudden suspension, acknowledging the impact on customers who lost access to the affected AI models.

“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,” Anthropic said. “This action does not adhere to those principles.”

The announcement marks the latest point of friction between Anthropic and the U.S. government, following a highly publicized dispute with the Department of Defense earlier this year that brought the company’s relationship with federal authorities into the spotlight.

The latest export restrictions are likely to intensify scrutiny of Anthropic’s advanced AI systems and their potential national security implications.