Anthropic suspends Fable 5 and Mythos 5 access following US export directive
Anthropic has disabled its Fable 5 and Mythos 5 models to adhere to a US government export control directive, sparking debate over security capabilities and market access.
Anthropic has suspended access to its Fable 5 and Mythos 5 artificial intelligence models to comply with an immediate export control directive issued by the United States government. The order, received at 5:21pm ET, mandates the cessation of access for all users identified as foreign nationals, regardless of their physical location. The AI firm confirmed the immediate shutdown of these specific models for all customers to ensure compliance with national security authorities.
The regulatory action coincides with a high-profile two-day summit in Beijing between US President Donald Trump and Chinese President Xi Jinping, marking the first visit by an American president to China since 2017. The agenda at the summit includes discussions on trade, artificial intelligence, and tensions in the Strait of Hormuz. Attendees at the gathering include prominent US technology leaders such as Elon Musk, Tim Cook, and Jensen Huang.
Market reaction to the broader geopolitical developments was positive, with US stock indices rising on the day of the summit. The Dow Jones Industrial Average gained 0.8 per cent, the S&P 500 rose 0.3 per cent, and the Nasdaq Composite climbed 0.2 per cent. Nvidia shares surged more than 2 per cent following news that the US approved H200 chip sales to Chinese firms.
Anthropic has expressed strong disagreement with the regulatory action, arguing that the capabilities identified in the directive are not unique to its technology. The firm noted that other publicly available models, such as OpenAI’s GPT-5.5, can discover similar vulnerabilities without requiring a bypass. Anthropic emphasised that such capabilities are commonly used by security defenders to keep systems safe.
The specific technical capabilities or vulnerabilities cited in the US government’s directive are not detailed in public records. The exact scope of the term "foreign national" as defined by the directive remains unclear, particularly regarding dual citizens or users accessing the models from US servers. The long-term impact of this directive on Anthropic’s global market share or competitive standing against rival models is not yet quantified.