The U.S. government ordered Anthropic on Friday, June 13, 2026, to immediately disable access to two of its most powerful AI models — Claude Fable 5 and Claude Mythos 5 — citing national security concerns. Anthropic confirmed it complied after receiving the directive at 5:21 pm ET, but publicly disputed the government’s reasoning.
The shutdown affects all users worldwide, not just the foreign nationals the export control order was nominally targeting. Access to Anthropic’s other models remains unaffected.
Mythos is Anthropic’s most capable model. Due to what the company described as its exceptional ability to identify security vulnerabilities — it found flaws in every major operating system and web browser it tested — Anthropic had kept it tightly restricted under a controlled program called Project Glasswing, sharing it with roughly 50 vetted organizations including Amazon, Apple, Google, Microsoft, and CrowdStrike for defensive cybersecurity work. Fable 5, released just three days before the shutdown, was a guardrail-fitted version of Mythos designed for general public use and had ranked as the most capable publicly available AI model according to benchmark tests from Vals AI.
Anthropic says the government’s underlying concern appears to be a claimed jailbreak of Fable 5, though only verbal evidence of a “potential narrow, non-universal jailbreak” has been provided. The company described the jailbreak as prompting the model to read a codebase and identify software flaws — a capability it says is already available in other public models, including OpenAI’s GPT-5.5, and is routinely used by cybersecurity professionals.
Anthropic pushed back sharply. “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,” the company wrote, warning that applying this standard industry-wide “would essentially halt all new model deployments for all frontier model providers.”
The shutdown carries significant business implications for Anthropic, which is widely expected to pursue an IPO this year. OpenAI CEO Sam Altman had previously criticized Anthropic’s cautious handling of Mythos as “fear-based marketing,” and the government’s action suggests that Anthropic’s own public warnings about the model’s risks may have contributed to the scrutiny that led to the shutdown.
Source: TechCrunch