# Cybersecurity Leaders Ask US to Lift Anthropic Restrictions > Source: > Published: 2026-06-15 23:49:51.948740+00:00 # Cybersecurity Leaders Ask US to Lift Anthropic Restrictions More than **120** cybersecurity and technology professionals signed an open letter urging the Trump administration to lift export-control restrictions on **Anthropic**'s Fable 5 and Mythos 5 models, according to **PYMNTS**. The letter, led by former **Facebook** Chief Security Officer **Alex Stamos**, was dated June 14 and addressed to Commerce Secretary **Howard Lutnick** and National Cyber Director **Sean Cairncross**, per **PYMNTS** and **Axios**. **Reuters** reports that signatories include security executives and researchers at **Adobe**, **Zoom**, **Sophos**, and **Nvidia**. The letter followed a US government directive that, per **Anthropic**'s official statement, required the company to disable Fable 5 and Mythos 5 for all customers to comply with export controls barring access to any foreign national. **Anthropic** said the government cited a narrow jailbreak -- asking the model to read a codebase and fix software flaws -- a capability the company says is also available in other publicly deployed models. ### What happened The US government issued an export control directive on June 12, 2026 directing **Anthropic** to suspend all access to Fable 5 and Mythos 5 by any foreign national -- including foreign national **Anthropic** employees -- whether inside or outside the United States, per **Anthropic**'s official statement. Compliance required **Anthropic** to disable the models for all customers. The company had launched Fable 5 and the underlying Mythos 5 base model on June 9, per **PYMNTS**. ### The open letter On June 14, more than **120** cybersecurity and technology professionals signed an open letter asking Commerce Secretary **Howard Lutnick** and National Cyber Director **Sean Cairncross** to lift the restrictions, according to **PYMNTS**. The effort is led by former **Facebook** Chief Security Officer **Alex Stamos**, now Chief Product Officer at Corridor, per **Axios**. Signatories include Luta Security CEO **Katie Moussouris**, SocialProof Security CEO **Rachel Tobac**, Veracode co-founder **Chris Wysopal**, computer scientist **Paul Vixie**, Sophos CEO **Joe Levy**, and **Nvidia** security researcher **Aaron Grattafiori**, per **Axios**. The letter, hosted at freefable.org, argues that the restrictions "have taken the best models away from defenders, created market uncertainty, and risked America's AI leadership without any real risk to justify it," per **Axios**. ### Government rationale and Anthropic's position **Anthropic** said in its statement that the government cited a narrow, non-universal jailbreak: a technique of asking the model to read a specific codebase and identify software flaws -- described by **Anthropic** as the "'fix this code' jailbreak." **Anthropic** reviewed a demonstration and found the vulnerabilities identified were previously known, minor, and discoverable using other publicly available models, including **OpenAI**'s GPT-5.5, per the company's statement. **Stamos** told **Axios** that Fable 5 creates "proofs of concept" for vulnerabilities -- useful for security defenders -- but that only Mythos 5 and Mythos Preview (previously limited to vetted participants in **Anthropic**'s Project Glasswing initiative) could autonomously chain vulnerabilities into full attack sequences. **Anthropic** said it disagrees with the directive and is working to restore access. ### Context and significance The confrontation sits at the intersection of export controls, AI governance, and defensive security practice. The open letter argues that defenders rely on frontier models to find and remediate vulnerabilities faster than adversaries, and that restricting the best domestic tools cedes ground as foreign models -- including open-source Chinese models such as Kimi 2.7, per **Axios** -- rapidly improve. **Anthropic**'s statement warned that applying this standard across the industry "would essentially halt all new model deployments for all frontier model providers." ### What to watch - •Whether Commerce Secretary **Lutnick** or National Cyber Director**Cairncross** respond publicly;**Stamos** told**Axios** the letter remains open to new signatures. - •Whether **Anthropic** succeeds in restoring access, potentially through a revised technical safeguard demonstration or updated government guidance. - •How this confrontation shapes export control precedent for AI models broadly, since **Anthropic** explicitly framed the standard as one that -- if applied uniformly -- would freeze frontier model deployment industry-wide. ## Scoring Rationale US export controls that actually disabled a major AI company's frontier models globally -- with coordinated industry pushback from 120+ security leaders -- constitute a landmark AI governance event with direct practitioner impact. The confrontation between Anthropic and the US government over model access sets precedent that could constrain future frontier model deployments industry-wide. Practice interview problems based on real data 1,500+ SQL & Python problems across 15 industry datasets — the exact type of data you work with. [Try 250 free problems](/problems)