Anthropic Shuts Down Fable 5 and Mythos 5 After US National Security Order

The US government ordered Anthropic on Friday to immediately suspend access to its two most advanced AI models, marking the first time a federal directive has forced a leading AI company to take publicly deployed models offline.

Anthropic received the order at 5:21 p.m. ET on June 12, 2026. Citing "national security authorities," the directive — signed by Commerce Secretary Howard Lutnick and prepared with the help of the Bureau of Industry and Security — instructed the company 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," according to Anthropic's official statement.

Because complying only for foreign nationals would have been technically unworkable, Anthropic disabled the models for all customers. The company confirmed access to all other Anthropic models — including Claude Opus 4.8 — was not affected.

What the Government Said — and What Anthropic Disputes

The government's stated concern is a jailbreak: a technique that could allow users to bypass certain safeguards in Fable 5.

According to Axios, the Commerce Department acted after another company claimed it had successfully jailbroken Mythos, alarming the administration about potential national security risks. The department had previously tried to get Anthropic to pause the release of the models before launch, but was unsuccessful.

Anthropic's response is a direct public challenge to the finding. In its official statement, the company said it had reviewed the specific technique cited by the government and found it produced "a small number of previously known, minor vulnerabilities" — not a new or serious jailbreak. "We have not even received a disclosure of a concerning non-universal potential jailbreak that led to a harmful result," Anthropic wrote.

The company disputed the directive on procedural and technical grounds: "As we have stated publicly, we believe the government should have the ability to block unsafe deployments, as part of a statutory process that is transparent, fair, clear, and grounded in technical facts. This action does not adhere to those principles."

Per CNBC, the letter from the Commerce Department did not provide specific technical details about its national security concern.

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The Backstory — Anthropic vs the US Government

Friday's shutdown is the latest confrontation in a deteriorating relationship between Anthropic and the Trump administration.

According to CNBC, the Department of Defense had previously declared Anthropic a supply chain risk after negotiations over safety guardrails on autonomous weapons and domestic surveillance collapsed. Anthropic subsequently sued the Trump administration over its blacklisting, and that litigation remains ongoing.

Just two days before the shutdown order, on June 10, Anthropic CEO Dario Amodei had published a sweeping policy essay calling for the government to have mandatory legal authority to block dangerous AI model releases — a call for more, not less, government oversight. The irony of the same government now exercising informal shutdown authority on its own models — without the transparent statutory process Amodei had called for — was not lost on observers.

NBC News noted the shutdown is "the first time a leading AI company has taken a publicly deployed model offline due to intervention from the federal government."

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Market Reaction and IPO Implications

Traders responded immediately.

According to CoinDesk, Anthropic's perpetual contract on Hyperliquid — a cash-settled instrument tracking where traders expect the company's equity to price — fell approximately 3.7% to around $1,627 on Saturday, down from post-launch highs.

The shutdown raises a structural question for Anthropic's pre-IPO valuation: if the government can unilaterally disable a company's flagship models citing a jailbreak it hasn't fully disclosed, how should investors price that regulatory risk into the company's public listing?

Gary Marcus, a frequent AI industry critic, posted on social media that the directive would likely accelerate the departure of Chinese-born AI researchers from US labs to China — the opposite effect of the stated national security goal. Anthropic said it would share more technical details about the specific jailbreak within 24 hours and that it was "working to restore access as soon as possible."

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Key Takeaways

• US Commerce Secretary Howard Lutnick sent a directive to Anthropic at 5:21 p.m. ET on June 12 ordering suspension of Fable 5 and Mythos 5 for all foreign nationals.
• Anthropic disabled both models for all customers to ensure compliance — a first in the AI industry.
• The government cited a jailbreak vulnerability; Anthropic disputes the severity, calling it "previously known, minor vulnerabilities."
• The directive was prepared with the Bureau of Industry and Security (Commerce Department).
• Anthropic's pre-IPO contract on Hyperliquid fell 3.7% on the news.
• All other Anthropic models, including Claude Opus 4.8, remain fully operational.

Sources

• Anthropic — Official Statement on Fable 5 and Mythos 5 Access
• CNBC — Anthropic disables access to Fable 5 and Mythos 5 to comply with government directive
• Axios — Trump admin blocks foreign access to Anthropic's most powerful AI
• NBC News — Anthropic suspends new AI models after government directive
• Bloomberg — Anthropic says US limits foreign access to Fable 5, Mythos 5
• CoinDesk — Anthropic's pre-IPO shares fall as US government shuts down its most powerful AI model
• Fortune — Anthropic disables Fable and Mythos AI models after US government bars foreign access

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