Anthropic said on Friday it will "abruptly disable" its most advanced AI models for all users after the US government ordered it to suspend access to the models for foreign nationals, citing national security concerns. The company received the export control directive to suspend access to Fable 5 and Mythos 5 for all foreign nationals, without being given specific details ​of its national security concern, ‌Anthropic said in a statement. It is Anthropic's understanding that the government believes there is a method of bypassing, or "jailbreaking," a safeguard that would prevent Fable ⁠5 from being used in identifying software vulnerabilities, the company said. The order comes just as a previous dispute between Trump administration officials and IPO-bound Anthropic showed signs of easing across parts of the US government. Anthropic's relationship with the government ruptured this year after it refused to allow ‌the US military to use its AI models for domestic surveillance and fully autonomous weapons systems. The government responded by putting Anthropic on a supply chain ⁠blacklist, set to take effect later in the year. Read moreStreamlining the kill chain: how AI is changing modern warfare The action also marks a major escalation of US efforts to halt foreign adversaries' AI capabilities. For years, US export controls have focused on the chips and tools that power AI rather than on restricting foreign access to AI itself. Anthropic said the government has given it only "verbal evidence of ​a potential narrow, non-universal jailbreak". "We disagree that the finding of a narrow potential jailbreak should be cause for recalling a commercial model deployed to hundreds ‌of millions of people," the company said. The government directive and Anthropic's response highlight growing tension between AI developers and regulators over how to assess risks from so-called "jailbreaks," or methods used to bypass model safeguards. As recently as Wednesday, Anthropic had called for greater US oversight of AI, including the ability to block models with unacceptable risks. It said, however, the government action on Friday did not follow principles of fair and fact-based regulation.