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Anthropic switched off Claude Fable 5 on June 12, 2026, after a U.S. government directive.

off-limits for

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What we know

Model: Fable 5 and Mythos
What happened: Access disabled for all users
Why: Anthropic complied with a U.S. government directive
In the meantime: New sessions fall back to Opus 4.8

Get pinged the moment it's back

The vigil

what people are saying on X

Anthropic

@AnthropicAI

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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 Show more

12:50 AM · Jun 13, 2026

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As a result of a US government directive, we are suspending access to Claude Fable 5 for all users. You can continue to use all other Claude models. Here’s what this means for you: Across Claude products, new sessions will run on your selected default model or Opus 4.8, and Show more

Anthropic

@AnthropicAI

12:51 AM · Jun 13, 2026

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I got a good nights sleep and I’m still just as angry about Anthropic’s choices. I enjoy working in AI so much and to have my access to the cutting edge models for my work rugpulled in an under the table fashion is appalling. I expected to be restricted eventually, but not Show more

1:19 PM · Jun 10, 2026

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Replying to @jeremyphoward

Anthropic has chosen the *opposite* of the safe path: they are allowing themselves, the current top lab, to use their top model for frontier AI research. They've said they'll sabotage others who try. This means the AI frontier advances, & power imbalance increases.

6:29 AM · Jun 10, 2026

386

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Lisan al Gaib

@scaling01

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Fable 5 refused 200 out of 200 ProgramBench tasks lmao

11:07 PM · Jun 11, 2026

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Replying to @bneyshabur

I've argued for the last eight months that this was the direction things were heading. In my view, concentrating these capabilities fundamentally slows scientific and technological progress and is net negative for humanity.

11:50 PM · Jun 9, 2026

159

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ClaudeDevs

@ClaudeDevs

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We’re rolling out changes to make Fable 5’s safeguards for frontier LLM development visible. Starting this week, flagged requests will visibly fall back to Opus 4.8—the same as our safeguards for cyber and bio. You will see this every time it happens. On the API, any flagged Show more

5:56 AM · Jun 11, 2026

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This is a super exciting release - Claude Fable 5 is the same underlying model as Mythos but with added safeguards. The benchmarks are great and it's SOTA on everything by a margin but I'll add that *qualitatively* also, this is a major-version-bump-deserving step change forward Show more

Claude

@claudeai

Fable 5 is state-of-the-art on nearly all tested benchmarks, with exceptional performance in software engineering, knowledge work, scientific research, and vision. The longer and more complex the task, the larger Fable 5’s lead over our other models.

Benchmark table titled Mythos 5 & Fable 5, comparing Claude Mythos 5 and Fable 5 against Claude Mythos Preview, Claude Opus 4.8, GPT 5.5, and Gemini 3.1 Pro.

6:10 PM · Jun 9, 2026

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Fable 5 pricing confirmed at $10/$50 The model will be available in the Pro, Max, Team and seat-based Enterprise plans at no additional cost until June 22nd Afterwards it will require usage credits

Lisan al Gaib

@scaling01

Claude Mythos and Fable 5 Benchmarks Anthropic is SOTA everywhere

5:11 PM · Jun 9, 2026

439

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ClaudeDevs

@ClaudeDevs

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If you’re having trouble accessing Claude Fable 5, try running /model claude-fable-5. In the Claude Code CLI, make sure to upgrade to 2.1.170. If you’re on the Claude Desktop app, update the latest version.

6:28 PM · Jun 9, 2026

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Working on AI for cancer? Sorry, I can't help you. Working on AI for Alzheimer's Disease? Sorry, I'm becoming a bit dumb when it comes to the AI part of it. Why don't everyone stop trying to do AI for Science & Tech? We can do it all gradually. You just have to be patient.

Behnam Neyshabur

@bneyshabur

This marks the beginning of a significant phase transition in the behavior of frontier AI labs and their relationship with the rest of the world 🧵

1:54 AM · Jun 10, 2026

369

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Lisan al Gaib

@scaling01

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claude-fable-5 👀

@M1Astra

New Claude model checkpoints (Possibly Mythos GA) - Claude Fable 5 - Claude Fruitcake EAP The new checkpoints were detected for testing over the weekend.

12:29 AM · Jun 9, 2026

639

Read 12 replies