US Government Orders AI Firm Anthropic to Block Foreign Nationals from Accessing New Models

At Washington’s request, Anthropic suddenly took its newest and most powerful AI models offline over the weekend. The American company said it had little choice after the White House demanded it block access for all foreign nationals, including its own employees. Abroad, the incident offered a sobering reminder that the US not only dominates frontier AI — its government also wields power over who gets to use it.

The Trump administration’s action was swift, sweeping, and imposed with little warning or explanation. The unprecedented shutdown of the Fable 5 and Mythos 5 models — which were already subject to safeguards limiting their use in “high-risk areas” — that followed gave new force to long-running arguments cautioning against relying on the US for critical technologies. It was fresh ammunition for the politicians, governments, and companies already arguing that they need to lead in the technology themselves.

According to a new report from Semafor, the White House’s decision to impose export restrictions on Anthropic’s Mythos was driven in part by fears that it had been accessed by a group linked to China. If the Chinese government actually had access to Mythos 5 or Fable 5, it would present a serious national security risk. The government could also attempt to reverse engineer the model through distillation, a method in which a “student” AI is trained on a more advanced model to replicate its behavior.

The White House has not confirmed this report, and a post on X by Trump adviser David Sacks did not mention China. Instead, Sacks focused on a reported ability for Fable and Mythos to be jailbroken, something that Anthropic has denied. Anthropic has not replied to a request for comment, though a spokesperson told Semafor that the government did not bring up China during its discussions around export controls.

According to the The Wall Street Journal, the export control directive that led to Anthropic cutting off access to Fable 5 and Mythos 5 was triggered in part by cybersecurity research from Amazon and conversations between CEO Andy Jassy and the White House. According to the report, the paper from Amazon claims that, through a series of prompts, it was able to get Fable 5 to serve up information that could be used in cyberattacks. Amazon has yet to respond to a request for comment.

Shortly after Jassy shared the company’s findings with the government, it made the call to block its use by foreign nationals. Complicating this issue is that many of Anthropic’s researchers are foreign-born, meaning they were barred from accessing their own product.

On Friday evening, the government ordered Anthropic to block access to Fable 5 and Mythos 5 for all foreign nations, both inside and outside the US, due to national security concerns. That order included employees of Anthropic. To meet those demands, the company has completely cut off access to the models for all customers.

In a statement, Anthropic said that while it was complying with the order, the government “did not provide specific details of its national security concern.” Instead, it claims that any evidence of potential jailbreak was provided verbally, and that the vulnerabilities discovered were minor and available via other models, including GPT 5.5.

Anthropic just announced Claude Fable 5, a new AI model it said is the most powerful model it has ever made widely available.

According to the company, Fable 5 “shows exceptional performance in software engineering, knowledge work, and vision,” with its lead over other models growing as tasks become longer and more complex.