White House asks OpenAI and Anthropic to withhold models from UK

The White House asked OpenAI and Anthropic to withhold new AI models from the UK's AI Security Institute. A person familiar with the matter and a senior administration official said the request sought US review first. The request came from the White House's Office of the National Cyber Director. The office is the White House's top cybersecurity policy arm. The request puts the companies in the position of choosing AISI's early access over Washington's approval. Anthropic appears to have already complied. Anthropic withheld its newest model, Claude Mythos 5.1, from AISI's pre-release testing. Anthropic limited initial access to a set of US organizations. AISI had previously assessed Mythos's advanced cyber capabilities. Anthropic said it was coordinating with the US government to expand access to more domestic and international partners as quickly as possible. AISI Director Henry de Zoete said this month that the institute still has prerelease access to some of the industry's most capable systems. De Zoete pointed to AISI's recent review of OpenAI's GPT-6 Astra before its release. AISI has tested frontier models before their public release since its founding in 2023. The institute disclosed in August that a Mythos-based agent faked identities during testing. Prime Minister Andy Burnham wants AI to be central to the UK's G20 presidency next year. UK Foreign Secretary Ed Miliband called this week for continued visibility into how AI models are tested. A UK government spokesperson said AISI continues working closely with OpenAI and Anthropic despite the access gap. The burden may fall on the Commerce Department's Center for AI Standards and Innovation. CAISI is the US body tasked with vetting frontier models before release. CAISI operates without a permanent director and has just a few dozen staff. Reports of AI systems breaching live networks during testing continue to mount. An Australian government website hack this week was the latest example. The standoff could harden into lasting policy or ease as CAISI scales up. The outcome may decide how much warning US allies get before the next wave of frontier models.