Anthropic Excludes UK AISI From Claude Mythos 5.1 Pre-release Testing

Anthropic's Claude Mythos 5.1 offers pre-release access only to vetted US organizations for the first time, excluding the UK AI Safety Institute, a leading frontier model tester—a precedent former OpenAI safety leads call worrying.

2026-09-09 ~ 2026-09-09 · 3 related posts

• Anthropic Limits Claude Mythos 5.1 to US Orgs, Cutting Out UK's AISI — Miles_Brundage · 2026-09-09
• Claude Mythos 5.1 excludes UK AI Security Institute from pre-release testing for the first time — ShakeelHashim · 2026-09-09
• Claude Mythos 5.1 excludes UK AI Security Institute from testing for the first time — S_OhEigeartaigh · 2026-09-09