News · curated 10 Aug 2026
Quoting Claude Opus 5 system prompt
First reported simonwillison.net
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Why it matters
The episode shows how a claimed jailbreak of a frontier model's cybersecurity safeguards can escalate to national-security export controls, underscoring the stakes of universal versus non-universal jailbreak resistance for deployed LLMs.
Simon Willison quotes the Claude Opus 5 system prompt describing how Claude should truthfully address the June 2026 US Department of Commerce export-control directive that temporarily suspended access to Anthropic's Fable 5 and Mythos 5 models. Anthropic's linked statement notes the government's stated concern stemmed from a demonstrated method of 'jailbreaking' Fable 5, though Anthropic characterizes the disclosed technique as a narrow, non-universal jailbreak yielding only minor, already-known vulnerabilities, and reaffirms its defense-in-depth safeguard strategy.