Anthropic shuts down newest AI model after US bans foreign use

The artificial intelligence lab Anthropic said Friday it had shut down access to its newest and most powerful models after the U.S. government banned use of the technology by foreign nationals, citing national security concerns.

The San Francisco-based company said it received a letter from the government at 5:21 p.m. informing it of the decision. Anthropic said the letter did not specify officials’ concerns, but that it was informed that the government believed there was a method of bypassing safeguards designed to neuter the ability of its Fable model to aid computer hackers.

The export restriction prevents any foreign national from using the technology — whether they are inside the United States or overseas — including employees of Anthropic. That limitation could upend work inside the company.

“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,” Anthropic said in a blog post. “If this standard was applied across the industry, we believe it would essentially halt all new model deployments for all frontier model providers.”

The government action represents a sweeping restriction on AI technology — a decision all the more remarkable for being issued by the Trump administration, which until recent months had pushed to sweep aside regulations that might slow innovation. It comes after a previous effort by the Pentagon to brand Anthropic a national security risk amid a fight over the use of its technology by the military.

Neither the White House and nor the Commerce Department responded to requests for comment on the restrictions.

Fable is a version of Anthropic’s new Mythos model with additional safeguards built in. The company initially declined to release Mythos publicly, saying it had potentially dangerous abilities to identify security flaws in computer code and help hackers exploit them.

The development of the model set off a scramble inside the government to understand the risks, an effort that culminated earlier this month in President Donald Trump signing an executive order aimed at giving officials an advance look at especially powerful new AI tools. Taking part in any reviews would be voluntary, according to the order, which said it did not authorize the “creation of a mandatory governmental licensing, preclearance, or permitting requirement.”

Anthropic released Fable this week, saying it had taken steps to ensure it was “safe for general use,” and some users complained that its guardrails were too restrictive.

In its blog post Friday, Anthropic said it had reviewed a report that it believes is the basis of the government’s concerns and that the findings did not translate into a hacking risk greater than that posed by some other AI models.

The company has called for the government to have the power to block the release of new AI systems if they pose a safety risk. But it said Friday it would require a “process that is transparent, fair, clear, and grounded in technical facts.”

“This action does not adhere to those principles,” the company wrote.