US forces Anthropic to suspend Fable 5 and Mythos 5

TL;DR:

  • A US Commerce Department export directive ordered Anthropic to cut off Fable 5 and Mythos 5 from all foreign nationals, prompting the company to disable both models for every customer.
  • Washington cited a method of “jailbreaking” Fable’s safeguards; Anthropic counters the evidence was a narrow, non-universal flaw that rival models share.
  • The move extends US export controls beyond chips to the models themselves — a shift with direct consequences for the UK firms that relied on the tools days after release.

For years, US export controls targeted the chips and tooling beneath artificial intelligence. This weekend Washington went after the models directly, ordering Anthropic to suspend access to its frontier systems, Fable 5 and Mythos 5, for any foreign national. Unable to enforce a citizenship test cleanly, Anthropic disabled both for all users worldwide; access to its other models was unaffected.

A disputed jailbreak

The directive, delivered Friday without detailed reasoning, rests on the government’s belief that a “jailbreak” could bypass Fable’s safeguards to surface software vulnerabilities. Anthropic disputes the severity, saying it has only seen verbal evidence of a narrow flaw that essentially amounts to asking the model to read a codebase and fix faults — a capability it says is widely available, including in OpenAI’s GPT-5.5. “We disagree that the finding of a narrow potential jailbreak should be cause for recalling a commercial model deployed to hundreds of millions of people,” the company said.

The order also caps a deteriorating relationship. As The Conversation set out, Anthropic and the Trump administration have clashed since early 2025 over regulation and the firm’s refusal to allow military use for surveillance and autonomous weapons — a dispute that already saw the Pentagon move to designate it a supply-chain risk. The suspension lands just as Anthropic pursues a US IPO.

Looking forward

Anthropic warns that applying this standard industry-wide “would essentially halt all new model deployments.” The episode arrives only days after Resultsense covered the public release of Fable 5, underscoring how abruptly access can vanish. For UK organisations — already weighing frontier-model cyber risk in banking — the practical takeaway is concentration risk: critical tools can be switched off by a foreign regulator overnight.

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