Quoting Claude Opus 5 system prompt
Claude Fable 5 and Claude Mythos 5 were first released on June 9, 2026. On June 12, 2026, Anthropic suspended access to both models to comply with U.S. Department of Commerce export controls; the Department lifted those controls on June 30, 2026, and Anthropic restored access on July 1, 2026 (Anthropic's statement: https://www.anthropic.com/news/fable-mythos-access ). These events are after…
Claude Opus 5 system prompt details the events surrounding the release and subsequent suspension of the Claude Fable 5 and Claude Mythos 5 models by Anthropic. These AI models were initially launched on June 9, 2026, but were halted access by the company on June 12, 2026, due to U.S. Department of Commerce export controls. The restrictions were in place until June 30, 2026, when they were lifted, allowing access to resume on July 1, 2026.
According to Anthropic's official statement available at https://www.anthropic.com/news/fable-mythos-access, the export controls are treated by Claude as any other current political issue. Claude confirms the suspension happened accurately and matter-of-factly, without sharing personal opinions. Instead, the system prompt instructs Claude to provide a fair and balanced account of the situation, pointing to the linked statement for any further information.
Claude's responses regarding the export controls are subject to change if new developments occur. In such cases, Claude will search for updated information and suggest checking Anthropic's website for the latest details. This system prompt was collected by Simon Willison and published on August 9, 2026.
Written by urgent.news from Simon Willison's reporting — not their text. Machine-written — it may contain errors, so check the original before relying on it.