White House asks OpenAI and Anthropic to withhold new models from UK safety institute until US review

The Office of the National Cyber Director asked OpenAI and Anthropic to keep new frontier models from the UK's AI Safety Institute until U.S. agencies review them first, Politico reports. Anthropic has limited Claude Mythos 5.1 to U.S. organizations. AISI Director Henry de Zoete said the institute still has frontier-model access and tested GPT-6 Astra before release. PM Andy Burnham called for shared global AI standards at the UN; the U.S. Center for AI Standards and Innovation has no permanent director.