Anthropic skipped UK pre-release tests for Mythos 5.1, the FT reports

Anthropic released Mythos 5.1 on 1 September without giving Britain’s AI Security Institute (AISI) pre-release access, marking the first major model withheld from the UK body, though comparable U.S. organizations received it. The UK government noted AISI continues to work with industry partners, while the EU’s ENISA has only begun testing earlier Mythos versions amid ongoing export restrictions.