US Federal Agencies Circumvent Ban to Privately Test Anthropic’s New Mythos Model

Anthropic has positioned Claude Mythos 5 as its most powerful cybersecurity model, making its capabilities and access controls consequential for critical infrastructure protection and AI governance. With the public-facing Fable 5 still blocked, the gap between government and civilian access to advanced models has fueled controversy over technological monopolies and double standards.

Anthropic recently announced that Mythos 5 had been cleared to come back online, but only for certain US critical infrastructure organizations, with no access for the general public. Fable 5 remains blocked. Anthropic did not disclose the exact announcement date, the number of authorized organizations or any financial amounts involved, prompting criticism from the online and open-source communities that it is using AI risks to entrench national and technological advantages.

Anthropic’s Mythos 5 can automatically identify software vulnerabilities. The White House had previously opposed giving another 70 companies access, citing national security risks and the allocation of computing resources. The case highlights the Trump administration’s balancing act between the AI arms race, control of critical computing capacity and cooperation with frontier AI companies. Reports did not disclose any transaction value.

The latest reports indicate that the U.S. government has reversed course and allowed about 100 trusted companies to use Anthropic’s Mythos 5, broadening access beyond the additional 70 companies previously blocked. However, available information did not specify the exact approval date, participating companies, usage fees or computing quotas. Details of the national security review requirements have yet to be announced.

Anthropic's Mythos and Fable are AI models designed for advanced reasoning and cybersecurity tasks. The tests involved the defenses of classified U.S. National Security Agency networks. A model capable of quickly identifying weaknesses in national-security systems could affect AI safety governance, government procurement and the Five Eyes alliance's plans for technological sovereignty. As of July 19, 2026, no publicly disclosed amount was associated with the matter.

Recent reports said Mythos penetrated NSA systems within hours during a government red-team test, prompting U.S. lawmakers to call for mandatory third-party testing. Foreign media later clarified that the test took place in a simulated environment and did not involve an actual intrusion into the NSA's classified networks. The U.S. government has also restricted accounts belonging to non-U.S. nationals from accessing Mythos and Fable. As of July 19, 2026, officials had not disclosed the test date, full results or the date the restrictions took effect.

Mythos and Fable are Anthropic’s latest AI models. The Trump administration intervened over national security risks and concerns that their safety guardrails could be jailbroken. The episode underscores government concerns about frontier-model capabilities, technology leakage and the progress of Chinese open-source AI. It has also intensified tensions between Washington’s regulatory authority and Silicon Valley’s autonomy in research and development.

The U.S. government ordered Anthropic to withdraw Mythos and Fable entirely within 90 minutes on the day the order was issued. Anthropic subsequently stopped offering both models. The U.S. Commerce Department also imposed strict licensing controls on the models. Reports have not disclosed the order’s exact date, any penalties or transaction amounts, while market attention has shifted to the potential opportunities for open-source and decentralized AI.

Anthropic’s Mythos AI model is positioned as a system with advanced cybersecurity capabilities. But its powerful offensive and defensive tools could also be misused, drawing scrutiny from the European Commission and financial regulators. Anthropic has pledged to comply with the EU’s AI Code of Practice, assess the model’s risks and take steps to mitigate them.

EU officials have now met with Anthropic for a briefing on cybersecurity concerns surrounding Mythos, while euro-area finance ministers have separately raised requirements concerning bank access. Available information does not disclose the exact date of the meeting, the number of banks affected or any transaction amounts. Attention will now turn to access permissions and risk-control standards.

Anthropic was designated a supply-chain risk on February 27 after refusing to allow the U.S. Defense Department to use Claude for “all lawful purposes,” insisting on exclusions for mass domestic surveillance and fully autonomous weapons. Trump also ordered federal agencies to stop using the model, giving existing users a six-month grace period. The dispute affects a $200 million defense contract and highlights the tension between national-security demand for frontier AI and safety limits.

Anthropic launched Project Glass Wings on April 7, giving more than 40 organizations access to Mythos Preview and pledging $100 million in usage credits and $4 million in donations. The model has already identified thousands of high-severity vulnerabilities. Bloomberg reported on April 16 that the White House was considering allowing major federal agencies to use it with safeguards. The CEO met the White House chief of staff and Treasury secretary on April 17, while Axios disclosed on April 19 that the National Security Agency had already been using the model.