Bombshell: US Government Forces Anthropic to Shut Down Fable 5 and Mythos 5
Nobody saw it coming: On June 12, 2026, the US government issued an export-control directive — and Anthropic had to act immediately. Its two flagship models, Fable 5 and Mythos 5, were abruptly disabled for all customers worldwide. No phase-out, no transition period.
The essentials
- Fable 5 + Mythos 5: suspended by government directive — immediately, for all users.
- Reason: The US government cites national security.
- All other Claude models remain available unchanged.
- Anthropic complies with the order but publicly objects to it.
The reason: an alleged “security flaw”
Authorities justify the move with national security concerns. Anthropic suspects a specific “jailbreak” method triggered it — one that sounds almost mundane: asking the model to read a codebase and fix any software flaws.
Anthropic pushes back
The company complies with the legal directive — but makes its position unmistakably clear:
“We are complying with the government’s legal directive and are removing access to Fable 5 and Mythos 5.”
At the same time, Anthropic argues these capabilities are widely available from other models and used daily by security professionals. The flaw is narrow, not universal — and the measure, in Anthropic’s view, non-transparent and technically unjustified.
Why this concerns the whole industry
The case sets a precedent: if an agency can switch off powerful AI models by directive overnight, it raises real questions about reliability and availability for any company relying on frontier models. The takeaway for users: scrutinize model dependencies and plan for fallback options.
Source: Anthropic — Statement on the US government directive, June 12, 2026.