The United States has slammed the door on British access to Anthropic’s most advanced AI models. London’s attempts to secure an exemption failed outright. The move exposes the UK’s fragile reliance on American AI infrastructure.

On June 12, the US Commerce Department ordered Anthropic to block all foreign users from its latest Fable 5 and Mythos 5 models. The reason: national security concerns over a potential “jailbreak” that could bypass safeguards. Anthropic complied by disabling access globally—Americans included—since it couldn’t enforce nationality-based controls fast enough.

Downing Street pushed for a carve-out for the UK, citing the models’ critical role in sectors like healthcare, finance, and defense. Officials lobbied the White House during the G7 summit, but a source close to President Trump said there was “zero chance” for any exemption. The rebuff was a stark reminder that UK firms have no say when American tech giants pull the plug.

The ban’s impact rippled through British industry. Companies relying on these AI models found their tools dead overnight. The UK’s AI minister emphasized the national security risks, noting the models power drones, counter-drone systems, and cybersecurity defenses. Yet the Pentagon took a harsher stance, having already cut ties with Anthropic months earlier.

The industry fired back. Over 80 cybersecurity leaders from firms like Nvidia and Adobe signed an open letter demanding a rollback. They argued the ban hinders efforts to identify and patch software vulnerabilities. They also pointed out rival models, including China’s Kimi 2.7, remain accessible, raising questions about the export control’s consistency.

Legal experts doubt the Commerce Department’s authority to block AI access remotely. AI models aren’t physically exported; they’re accessed online. The legality of these controls is murky, but enforcement proceeds regardless.

This incident underscores a growing push for “sovereign AI.” The UK government has already committed £500 million to build domestic AI capabilities. Private investors are backing a £1 billion effort to create fully sovereign AI infrastructure. The Anthropic shutdown has sharpened the urgency. It’s no longer theoretical—British firms must prepare for sudden tech blackouts.

Across the Atlantic, the G7 summit wrestled with fallout from the US export controls. European leaders voiced frustration at being cut off alongside other allies. The episode confirmed fears that American technology comes with a “kill switch” that can be flipped without warning.

European officials insist trusted partners deserve better treatment and warn that dependencies on foreign AI threaten strategic autonomy. The export restrictions collided with Europe’s plans to secure AI supply chains under the Pax Silica initiative. The move has hardened resolve to build homegrown alternatives and reduce reliance on US providers.

Anthropic’s CEO attended the G7 to face questions from allies. The Trump administration claims its AI export rules set a global gold standard. Yet the ban’s blunt application has created a diplomatic headache and strengthened calls for independent AI ecosystems.

For the UK, the message is clear: dependence on foreign AI carries real risk. When Washington pulls the plug, there is no veto or workaround. British businesses and government now face a choice—accept technological vulnerability or invest heavily in homegrown AI resilience.