Anthropic, from the US government export control instruction after Claude Fable 5 And Claude Mythos 5 closed access to its models for all customers. The company announced that the decision targets access by foreign nationals. Despite this, Anthropic has disabled two models for everyone to safely carry out the onboarding process.
The decision comes after Anthropic introduced two new models this week. Company, Claude Mythos 5 planned to keep its model limited to Project Glasswing participants. Against this Claude Fable 5stood out as a model that opened up to a wider customer base. However, the letter sent by the US administration practically made it impossible for the company to maintain this distinction.
The history of the model family is that Anthropic has previously offered it with limited access. Claude Mythos Preview extends to version. Mythos Preview was created for security research purposes and has demonstrated high ability to find software vulnerabilities. Companies and research partners within Project Glasswing have identified numerous security issues using this model. Mozilla also announced that it has fixed hundreds of security vulnerabilities thanks to Mythos Preview.
Anthropic added several security restrictions when making Fable 5 available to the general public. However, these limitations brought criticism from some users who wanted to benefit from the model’s capabilities. The company made changes after launch to adjust the balance between security measures and usability. However, according to Axios, US Secretary of Commerce Howard Lutnick completely changed the process with the letter he sent to Anthropic CEO Dario Amodei.
US government introduced licensing requirements for Fable 5 and Mythos 5
According to Axios, the Ministry of Commerce, License to export, re-export, or transfer within the United States to foreign persons the Mythos 5 and Fable 5 models He asked for the condition. The news included information that the management took this step for national security reasons after another company claimed that it could jailbreak Mythos. In addition, Axios wrote that the Trump administration previously tried to prevent Anthropic from publishing the model, but failed to do so.
Anthropic, in its own statement, stated that the government letter did not provide details about the private security concern. The company understands that the government A jailbreak method for Fable 5 learned and made this method the reason for the decision. Anthropic stated that it examined the demonstration of this technique and found that the method only found some previously known, small-scale vulnerabilities. Additionally, the company argued that other publicly available models could find similar vulnerabilities without any circumvention techniques.
In its statement, Anthropic stated that the decision was based on a narrow circumvention method. According to the company, this method does not mean a universal jailbreak. However, the company stated that these capabilities are also available in other models and examples include: OpenAI GPT-5.5 He stated that the model was also included. Anthropic attributed the government’s decision to a misunderstanding and announced that it would work to restore access.
This outage had immediate consequences for teams using Claude products. According to Claude’s official Opus 4.8 It will open with . Existing Fable 5 sessions will end with the error message. On the Claude Platform side, API requests sent to Fable 5 will return errors and developers will move their integrations to other Claude models.
Fable 5 and Mythos 5 were listed as high-capacity models in Anthropic’s documentation. The company for two models 1 million token context window And It went up to 128 thousand tokens was giving support. On the pricing side, Anthropic, $10 for 1 million login tokens, $50 for 1 million exit tokens shared his knowledge. These values made the models important for long code bases, security research, and autonomous software tasks.
In its announcement on June 9, Anthropic said that Fable 5 and Mythos 5 can run independent missions for longer than previous Claude models. The company has positioned Mythos 5 for security advocates and infrastructure providers, and Fable 5 for its broader customer base. In the announcement, Stripe 50 million lines of Ruby code base It was also stated that he completed a major transition work in one day with the help of Fable 5.
Other Claude models are not affected by this decision. Anthropic is asking customers to temporarily redirect Fable 5 and Mythos 5-dependent workflows to other models. The company also announced that it will share more information in the next 24 hours. The real change for users comes when Fable 5 sessions and API calls now error out directly.