Artificial intelligence (AI) company Anthropic has blocked access to its newly released cutting-edge artificial intelligence software following orders from the U.S. government.
Citing national security concerns, the company said in a blog post published Friday that government agencies have directed it to prohibit all foreign nationals from accessing its AI models Fable 5 and Mythos 5.
The ban also affects foreign nationals currently in the United States, including foreign nationals who work for Anthropic. As a result of this order, the company was forced to suddenly cut off access to everyone.
The artificial intelligence behind Anthropic’s Mythos AI model is particularly good at detecting software vulnerabilities, some of which remain undiscovered for decades. This feature has previously been used by US authorities and select companies to fill security gaps. However, there have been concerns from the beginning that such AI could be turned into dangerous cyberweapons in the wrong hands.
The Fable 5 model, which was just released this week, is based on Mythos technology, but its cybersecurity and biotech features are blocked. Mythos 5 is a private, full version and should continue to be used only by government agencies and selected corporate partners to power their systems.
Antropic stressed that it has so far received only partial information from the government. The company said its assessment had considered the report that likely triggered the order. Anthropic experts concluded that this refers to the limited ability to use AI to review specific program code and correct errors.
The company emphasized that models from other providers also have this feature, such as rival OpenAI’s GPT-5.5. Anthropic said it disagrees that hundreds of millions of users’ software should be blocked for this reason and said Fable 5’s security measures have been thoroughly tested.
