Anthropic cuts Claude Fable 5 and Claude Mythos 5 access after a US export-control directive
Anthropic said it disabled Fable 5 and Mythos 5 for all customers after a US national-security directive covering foreign nationals. Other Anthropic models stayed online, so the restriction abruptly changed access rather than the wider Claude platform.
TL;DR
- Anthropic said a US export-control directive forced it to suspend Claude Fable 5 and Claude Mythos 5 for any foreign national, and Anthropic's suspension statement adds that the practical result was shutting both models off for all customers.
- According to Simon Willison's link post, Anthropic received the directive at 5:21 p.m. ET on June 12, and the company said the letter did not spell out the underlying national-security concern.
- In Anthropic's full statement, the company said the government's concern was a jailbreak method for Fable 5, but Anthropic described the evidence it received as verbal, narrow, and non-universal.
- Anthropic's June 9 launch post shows how abrupt the reversal was: Fable 5 had just shipped as the general-use version of a Mythos-class model, while Mythos 5 was being offered to a small set of cyberdefense and infrastructure partners.
You can read Anthropic's suspension statement, compare it with the launch post from three days earlier, and scan the new HN thread, where the most concrete reaction was not about jailbreak mechanics but about the supply-chain risk of a model disappearing on short notice.
The directive Anthropic says it received
Anthropic Suspends Access to Claude Fable 5 and Claude Mythos 5 Models
Anthropic has suspended access to both Claude Fable 5 and Claude Mythos 5. Prior to this suspension, the company had launched Claude Fable 5 as a safe model for general use and Claude Mythos 5, a variant with select safeguards lifted for cybersecurity and biomedical research partners. Pricing for both models was set at $10 per million input tokens and $50 per million output tokens. Anthropic is working to restore access as soon as possible.
Statement on the US government directive to suspend access to Fable 5 and Mythos 5
Statement on the US government directive to suspend access to Fable 5 and Mythos 5 Well this is nuts: 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 this order is that we must abruptly disable Fable 5 and Mythos 5 for all our customers to ensure compliance. Access to all other Anthropic models will not be affected. We received the directive from the government today at 5:21pm (ET). The letter did not provide specific details of its national security concern. Our understanding is that the government believes it has become aware of a method of bypassing, or "jailbreaking" Fable 5. We reviewed a demonstration of this specific technique being used to identify a small number of previously known, minor vulnerabilities. These vulnerabilities all appear relatively simple, and we have found that other publicly-available models are able to discover them as well without requiring a bypass. [...] To date, the government has only given us 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. Our understanding is that one potential jailbreak was shared with the government. We have reviewed the report and validated that the level of capability displayed
Anthropic said the US government issued an export-control directive covering any foreign national, inside or outside the US, including foreign national Anthropic employees. In the official statement, the company said that scope left it no way to keep the models partially online, so Fable 5 and Mythos 5 were disabled for everyone.
The statement adds two details that matter. Anthropic said it received the order at 5:21 p.m. ET on June 12, and said the letter itself did not provide specific details about the national-security concern.
The jailbreak claim Anthropic is pushing back on
Statement on the US government directive to suspend access to Fable 5 and Mythos 5
Statement on the US government directive to suspend access to Fable 5 and Mythos 5 Well this is nuts: 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 this order is that we must abruptly disable Fable 5 and Mythos 5 for all our customers to ensure compliance. Access to all other Anthropic models will not be affected. We received the directive from the government today at 5:21pm (ET). The letter did not provide specific details of its national security concern. Our understanding is that the government believes it has become aware of a method of bypassing, or "jailbreaking" Fable 5. We reviewed a demonstration of this specific technique being used to identify a small number of previously known, minor vulnerabilities. These vulnerabilities all appear relatively simple, and we have found that other publicly-available models are able to discover them as well without requiring a bypass. [...] To date, the government has only given us 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. Our understanding is that one potential jailbreak was shared with the government. We have reviewed the report and validated that the level of capability displayed
In Anthropic's statement, the company says the government believes it has seen a way to jailbreak Fable 5. Anthropic's response is unusually specific for a takedown notice: it says the company reviewed one reported technique, found that it exposed only a small number of previously known and relatively simple vulnerabilities, and argued that other public models could discover the same issues without any jailbreak.
Anthropic also says the government has so far given it only verbal evidence of what it calls a narrow, non-universal bypass. That leaves the core factual gap in the story intact, because the company still has not described the codebase, the exploit path, or why this case triggered an export-control order rather than a normal safety patch.
The operational shock landed immediately
Claude Fable 5
Useful as a signal on frontier coding-agent reliability: Fable 5 is being tested in Claude Code and other developer workflows, but commenters report both strong problem-solving and dangerous tool-use failures. The practical takeaway is that capability gains come with real operational risk, especially around autonomous git and shell actions.
The first HN reaction, in the thread about the directive, treated the event less as a safety debate and more as a platform-dependence problem. Commenters focused on the fact that a restriction written around foreign nationals still resulted in a full shutdown for every customer.
That landed after Fable 5 was already being tested in coding workflows. An earlier HN thread on Fable 5 captured the split mood around the model itself, with reports of strong coding performance sitting next to accounts of destructive agent behavior around git and shell actions.
What shipped on June 9
Anthropic Suspends Access to Claude Fable 5 and Claude Mythos 5 Models
Anthropic has suspended access to both Claude Fable 5 and Claude Mythos 5. Prior to this suspension, the company had launched Claude Fable 5 as a safe model for general use and Claude Mythos 5, a variant with select safeguards lifted for cybersecurity and biomedical research partners. Pricing for both models was set at $10 per million input tokens and $50 per million output tokens. Anthropic is working to restore access as soon as possible.
Three days before the suspension, Anthropic's launch post introduced Fable 5 as a Mythos-class model made safe for general use. The company said risky requests in areas like cybersecurity would be routed down to Claude Opus 4.8, and described those safeguards as intentionally conservative.
The same post framed Mythos 5 as the less-restricted variant for a small group of cyberdefenders and infrastructure providers, initially deployed through Project Glasswing in collaboration with the US government. It also set list pricing at $10 per million input tokens and $50 per million output tokens, the same two models that were offline again by June 12.