In June 2026, Anthropic disabled its frontier models "Claude Fable 5" and "Claude Mythos 5" for all users worldwide just after launch, following a US export-control order. No detailed explanation has been provided by the administration, and both models remained offline as of June 18.
June 12, 2026 · Anthropic
Three Days After Launch, Anthropic's Top Models Are Pulled Offline
A US Commerce Department export control directive ordered access to "Claude Fable 5" and "Mythos 5" cut off for foreign nationals. To comply, the company disabled both models for all users — and as of June 18 still cannot distribute either one.
Jun 9
Both models released
3 days
Until the directive arrived
All
Users locked out to comply
The capability gap that drew scrutiny
Long-horizon coding: Fable/Mythos 5 class vs the prior Opus 4.8 on FrontierCode Diamond
More than double the prior model — strength on long, complex autonomous tasks.
Benchmark scores (Fable 5 / Mythos 5 class)
SWE-Bench Pro (agentic coding) 80.3%
ExploitBench (cybersecurity) 78.0%
BioMysteryBench hard 46.1%
Strong cybersecurity capability was treated as the core national-security risk.
The directive
Cited "national security concerns" and a possible jailbreak bypassing Fable 5's guardrails — but gave no specific technical detail. Foreign employees blocked, inside or outside the US. Talks with the administration on June 15–16 did not lift the controls.
The pushback
Researchers' open letter calls the controls excessive, argues Fable 5 is on par with rival models that face no such measures, and warns the rules strip defenders of the best available tool.
Not an isolated event
An extension of ongoing friction between Anthropic and the Trump administration.
Pentagon "supply chain risk" litigation
→
Security concerns raised to officials
→
Export controls — models undistributable
Exactly what the company is being faulted for, and the course of talks, remain undisclosed.
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