SHORT ANSWER
● Why: US government export control directive citing national security — another company claimed to have jailbroken Mythos 5
● When: Directive received 5:21 PM ET on June 12, 2026 — three days after Fable 5 launched
● Who issued it: Commerce Secretary Howard Lutnick, letter addressed to Anthropic CEO Dario Amodei
● Anthropic's position: Disagrees — says no universal jailbreak found in thousands of hours of red-teaming
● What's still available: Claude Opus 4.8, Sonnet 4.6, Haiku 4.5 — all unaffected
● When it comes back: No date. Anthropic says "as soon as possible"
The Full Timeline - From Launch to Shutdown in 72 Hours
| Date |
Event |
| April 2026 |
Anthropic launches Claude Mythos Preview, restricted to ~200 Project Glasswing security partners. Captivates US government with autonomous cybersecurity capabilities |
| ~June 2, 2026 |
President Trump signs executive order creating a voluntary framework for the government to vet national security risks of advanced AI before public release |
| June 9, 2026 |
Anthropic publicly launches Fable 5 (Mythos-class, public access) and Mythos 5 (restricted to Glasswing partners). Fable 5 scores 80.3% SWE-Bench Pro. Free for all subscribers until June 22 |
| June 9-11 |
Fable 5 in developer hands for 72 hours. Stripe migrates a 50-million-line codebase in one day. Another unnamed company claims to find a jailbreak method for Mythos |
| June 12, 5:21 PM ET |
Commerce Secretary Lutnick sends letter to Anthropic CEO Dario Amodei. Export control directive: suspend all access to Fable 5 and Mythos 5 for any foreign national, inside or outside the US, including foreign national Anthropic employees |
| June 12, evening |
Anthropic disables both models for ALL users worldwide — not just foreign nationals — because it has no reliable way to verify user nationality at scale |
| June 13-14 |
Both models remain offline. Anthropic disputes the action, says "working to restore access as soon as possible." No timeline given |
The Specific Shutdown Reason - What the Government Claims
An administration official told Axios the Commerce Department decided to take action after another company claimed it was able to jailbreak Mythos, alarming the administration about possible national security risks. The letter from Commerce Secretary Lutnick to Dario Amodei did not specify the national security concern or name the company that claimed the jailbreak.
The concern: Mythos-class models have demonstrated the ability to autonomously discover and chain zero-day exploits across major operating systems and browsers. In Glasswing partner testing, Mozilla alone said it resolved hundreds of vulnerabilities using Mythos Preview. The government's fear is that a jailbreak bypassing Fable 5's safety classifier — which routes cybersecurity queries to the less capable Opus 4.8 — would expose this autonomous exploit capability to any user, including state-sponsored actors.
Why Anthropic Disagrees
Anthropic's statement is explicit: thousands of hours of pre-launch red-teaming by the US government, UK AI Safety Institute, and multiple private third parties found no universal jailbreak — a jailbreak that can very broadly bypass the model's safeguards, unblocking a wide range of cyber capabilities. Anthropic suspects a perfect jailbreak resistance is not currently possible for any model provider.
The key distinction Anthropic is making: a narrow jailbreak (bypasses the classifier for a specific class of queries) is fundamentally different from a universal jailbreak (broadly removes all safety routing). Anthropic argues that even if the unnamed company found a narrow bypass, Fable 5's safeguards remain substantially more effective than those of any previously deployed model — and a narrow bypass in Fable 5 is not more dangerous than equivalent vulnerabilities in GPT-5.5 or Grok 4.3, which remain available to foreign nationals without restriction.
The argument Anthropic is making to the government:
- No tester found a universal jailbreak despite thousands of hours of red-teaming
- Fable 5's safeguards are more effective than any prior deployed model
- A narrow jailbreak in Fable 5 is less dangerous than capabilities already available in GPT-5.5 or Grok 4.3 without export controls
- Disabling Fable 5 worldwide harms US companies and developers, not just foreign actors
- The correct response to a narrow jailbreak is a targeted fix, not a global suspension
Why Anthropic Disabled It for Everyone, Not Just Foreign Nationals
The directive targeted foreign nationals specifically. So why did Anthropic disable Fable 5 for every user worldwide, including US citizens?
Because there is currently no reliable technical mechanism to verify user nationality at the API level. Anthropic has no system that can confirm with legal certainty whether an API caller is a US citizen or a foreign national. An API key can be shared, a company's workforce may include foreign nationals, a VPN masks location, and a US-registered company may have foreign-national employees accessing the system. Rather than risk inadvertently violating the export control directive — which carries serious legal consequences — Anthropic took the conservative compliance position: disable access universally until the dispute with the government is resolved.
What to Use Instead Right Now
| Model |
Status |
Best replacement for |
| claude-fable-5 |
DISABLED |
— |
| claude-opus-4-8 |
Available |
Hard coding, complex reasoning — 69.2% SWE-Bench Pro |
| claude-sonnet-4-6 |
Available |
Everyday tasks, faster and cheaper than Opus |
| claude-haiku-4-5 |
Available |
High-volume, low-latency tasks |
Frequently Asked Questions
When will Fable 5 come back?
No date has been given. Anthropic says it is working to restore access "as soon as possible" and believes the suspension is a misunderstanding. Restoration depends on resolving the dispute with the Commerce Department — either demonstrating the claimed jailbreak is too narrow to justify the directive, or implementing technical controls that satisfy the government's nationality verification requirement. This could take days or weeks.
Is this permanent? Is Fable 5 gone forever?
Not permanently. This is an export control directive, not a product cancellation. Anthropic has a strong commercial and legal incentive to restore access — Fable 5 was its flagship product and is central to the October 2026 IPO narrative. The directive can be resolved through negotiation with the Commerce Department, technical updates to the model, or legal challenge. Anthropic calling it a "misunderstanding" signals they are pursuing a negotiated resolution, not accepting a permanent ban.
Which company found the jailbreak?
The administration official who spoke to Axios did not name the company. Anthropic's statement also does not name it. It is described only as "another company" — distinct from Anthropic's own red-team testers or the government's testers — that claimed to find a method to bypass Mythos. The claim has not been independently verified or published.
Does this affect other Claude models?
No. Claude Opus 4.8, Sonnet 4.6, Haiku 4.5, and all other Claude models are fully available. The directive specifically names Fable 5 and Mythos 5. Mythos Preview (the April 2026 Glasswing-restricted model) is also not mentioned in the directive — though Glasswing partners should verify their access directly.
Primary source: Anthropic official statement. Full analysis: US Government suspends Fable 5 and Mythos 5 — full story. For all AI news: June 2026 AI news calendar.