Fable 5 was beating GPT 5.5 on every major benchmark. Then the US government pulled it offline.
Anthropic's Fable 5, which briefly became the most capable AI model, outperformed OpenAI's GPT 5.5 on various benchmarks before the US government ordered its suspension due to national security concerns. This directive came just three days after its public release, during which it showcased advanced reasoning capabilities.
WPN Brief
- What Happened
Anthropic's Fable 5, which briefly became the most capable AI model, outperformed OpenAI's GPT 5.5 on various benchmarks before the US government ordered its suspension due to national security concerns. This directive came just three days after its public release, during which it showcased advanced reasoning capabilities.
- Why It Matters
The shutdown of Fable 5 and its counterpart, Mythos 5, represents a significant setback for Anthropic, impacting its competitive edge in the AI market and limiting access to its advanced technologies for users globally.
- The Bigger Picture
This incident highlights ongoing tensions between technological advancement and regulatory oversight, as governments grapple with the implications of powerful AI systems. The intervention reflects broader concerns about national security and the potential misuse of AI technologies, raising questions about the balance between innovation and safety.
Related Reports
More coverage on this story
10 reports across the wire
US government orders Anthropic to kill Fable 5 and Mythos 5 in unprecedented AI model recall
The US government has mandated Anthropic to suspend access to its advanced AI models, Fable 5 and Mythos 5, marking an unprecedented intervention in the commercial AI sector. This directive, received on June 12, cites national security concerns and aims to prevent potential misuse of these technologies.
Anthropic says it has taken its latest AI models offline to comply with new export controls
Anthropic has taken its latest AI models, Fable 5 and Mythos 5, offline in compliance with a directive from the Trump administration aimed at preventing their use by foreign nationals, citing national security concerns. This decision marks a significant intervention in the AI sector, reflecting ongoing tensions between technology companies and government regulations.
Anthropic to disable its most advanced AI models after US order limiting foreign access
Anthropic announced it will abruptly disable its most advanced AI models, Fable 5 and Mythos 5, for all users following a US government order that restricts access for foreign nationals due to national security concerns. The company stated that it was not provided with specific details regarding these concerns.
US government forces Anthropic to disable Claude Fable 5 and Mythos 5 for all customers worldwide
The US government has mandated Anthropic to disable access to its AI models, Claude Fable 5 and Mythos 5, for all customers globally, citing national security concerns and potential jailbreak risks. This directive marks a significant intervention in the AI sector, received on June 12, 2026.
Claude Fable 5 outpaces GPT-5.5 by 13 points on FrontierMath's toughest problems
Anthropic's Claude Fable 5 has achieved an impressive 88 percent accuracy on the most challenging problems in FrontierMath, significantly outperforming OpenAI's GPT-5.5, which scored around 75 percent. This marks a substantial improvement from the previous model, Opus 4.5, which had an accuracy below 10 percent in early 2026.
Anthropic launches powerful Fable 5 model publicly, while keeping Mythos restricted over cybersecurity concerns
Anthropic has publicly launched its new AI model, Claude Fable 5, while keeping its advanced Mythos model restricted due to cybersecurity concerns. The Fable 5 model is designed to excel in various tasks, including software engineering, and follows a period of limited access where users reported significant security vulnerabilities.
Anthropic says it believes the US government's export control order for Mythos 5 and Fable 5 is a "misunderstanding" and that it is working to restore access (Ananya Palyekar/Reuters)
Anthropic has been ordered by the U.S. government to suspend access to its advanced AI models, Mythos 5 and Fable 5, for all foreign nationals, citing national security concerns. The company believes this directive is a misunderstanding and is actively working to restore access.
Amazon’s CEO reportedly triggered the government crackdown that shut down Anthropic’s most powerful AI
Amazon CEO Andy Jassy reportedly raised security concerns regarding Anthropic's advanced AI models, Fable 5 and Mythos 5, which prompted the U.S. government to order their shutdown for all users due to national security risks. This directive was issued on June 12, 2026, and led to significant intervention in the AI sector.
Anthropic releases ‘safe’ version of Claude Mythos AI model to public
Anthropic has released Claude Fable 5, a new version of its advanced Mythos AI model, to the public after months of restricted access due to cybersecurity concerns. This model is designed to excel in various tasks, including software engineering and knowledge work, while incorporating safeguards to prevent misuse in sensitive areas.
Anthropic says it is disabling Fable 5 and Mythos 5 for all customers after the US government issued an export control order, citing national security concerns (Anthropic)
Anthropic has announced the disabling of its AI models, Fable 5 and Mythos 5, for all customers following a directive from the US government that cited national security concerns. This decision comes after the government issued an export control order, leading to immediate suspension of access to these advanced AI technologies.