AI giant Anthropic said on Friday it has taken its latest artificial intelligence models, known as Fable 5 and Mythos 5, offline to comply with a directive from the Trump administration to prevent their use by foreign nationals.

The export controls mark the U.S. government’s most significant step to date to restrict access to the most advanced AI models. Anthropic released Fable widely this week. That model is a limited version of the even more advanced Mythos, to which the company has tightly limited access due to cybersecurity fears.

In a statement, Anthropic said it disagrees with the government’s handling of the matter, saying it received the directive from the U.S. administration on Friday afternoon and that it did not specify the national security concerns.

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

Anthropic called it a “misunderstanding” and said it hopes to restore access to the models “as soon as possible.”

The Commerce Department did not immediately respond to a request for comment.

The action comes 10 days after U.S. President Donald Trump signed an executive order to establish a framework for the federal government to vet the national security risks of the most advanced AI systems for up to a month before their public release. Participation by AI developers would be voluntary, the order said.

While debuting Mythos in April, Anthropic said the ⁠model’s ability to find software flaws at scale could, if misused, pose serious risks to economies, public safety and national security.

That same month, Bank of Canada governor Tiff Macklem told reporters during a call from the sidelines of the International Monetary Fund’s spring meetings that there had been a fair amount of discussion about the model at the forum.

But Macklem emphasized that Mythos is not a one-off event and that the nature of AI development means firms, regulators and policymakers need to put plans in place to grapple with this rapidly evolving technology.

Whether it’s Mythos or another AI model, Macklem said, the ability of these new technologies to both expose and exploit vulnerabilities “puts a premium” on having strong cybersecurity protections in place.