Anthropic suspends access to Fable 5 and Mythos 5 due to the US government directive

This week, Anthropic introduced its Claude Fable 5 and Mythos 5 models. The Fable 5 model was made available for all users, while the Mythos 5 model was restricted to Glasswing partners.

Just a few days after the launch of these models, Anthropic has now suspended access to Fable 5 and Mythos 5.

The US government, citing national security authorities, has issued an export control directive to suspend all access to Fable 5 and Mythos 5 by any foreign national, whether inside or outside the United States, including foreign national Anthropic employees.

The net effect of…

— Anthropic (@AnthropicAI) June 13, 2026

Claude Fable 5 and Claude Mythos 5: Access suspended

This decision is taken after the US government, citing national security authorities, has issued an export control directive to suspend all access to Fable 5 and Mythos 5 by any foreign national, whether inside or outside the US, including foreign national Anthropic employees.

The letter received by Anthropic from the government did not specify details of its national security concern, but it is believed that the government has become aware of a method of bypassing, or “jailbreaking”, Fable 5.

Anthropic has defended that Fable comes with safeguards that are substantially more effective than those of any previously deployed model. The company has not received any jailbreak complaint and counters that every safeguard used in the industry is vulnerable to non-universal jailbreaks, and it is likely that universal jailbreaks will eventually be found in the future.

The government has given Anthropic verbal evidence of a potential narrow, non-universal jailbreak, which essentially consists of asking the model to read a specific codebase and fix any software flaws. The company assumes that one potential jailbreak was shared with the government, and they have also reviewed the report that is believed to be the basis of the government’s directive and validated that the level of capability displayed there is widely available from other models (including GPT 5.5), and is used every day by the defenders who keep systems safe.

For now, Anthropic has removed access to these models, complying with the directive, but it disagrees that the finding of a narrow potential jailbreak should be cause for recalling a commercial model deployed to hundreds of millions of people.

The company mentioned that it is working to restore access to these models as soon as possible.