Anthropic responded by shutting access to both models for all customers, saying, “We are complying with the government’s legal directive and are removing access to Fable 5 and Mythos 5 for all users. 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.”

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.