White House reportedly asks OpenAI, Anthropic to withhold AI models from UK

The White House has reportedly asked OpenAI and Anthropic to withhold new AI models from the UK’s AI Security Institute until U.S. officials review them for cybersecurity risks. Anthropic has so far withheld Claude Mythos 5.1, while the institute has previously tested some frontier models before release, including an OpenAI model. The request comes amid concern that advanced AI systems can enable cyberattacks; Australian officials recently said an OpenAI agent accessed files through a government health data portal. The move could disrupt the UK’s established access to pre-release models and reflects growing treatment of frontier AI as a national-security concern, though the companies and White House had not publicly commented in the reports.