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.

In its statement, the company lays out the steps it took to safeguard Fable and Mythos, including working with the US and UK governments and changing its data retention policy to help track attempts to use them for malicious purposes. It goes on to say that:

We have not even received a disclosure of a concerning non-universal potential jailbreak that led to a harmful result. The potential jailbreaks that have been disclosed to us are either entirely benign responses or are minor findings that provide no Mythos-specific uplift.