Senate hearing revelation — Claude Mythos 'broke into almost all of our classified systems, not in weeks, but in hours' — 100+ cybersecurity experts sign letter urging June 12 export-control reversal
A Senate hearing revealed that Claude Mythos 'broke into almost all of our classified systems, not in weeks, but in hours' — the foundational evidence behind the June 12 administration directive that restricted Mythos 5 and Fable 5 to U.S. citizens, knocking both offline for everyone. More than 100 cybersecurity experts signed a letter urging reversal — arguing these are precisely the tools defenders need.
The substantive piece is the Senate-hearing classified-systems revelation as policy-rationale source. The June 12 export-control directive that knocked Fable 5 + Mythos offline previously lacked specific public-disclosure rationale. The Senate hearing testimony — Mythos breaching classified systems in hours not weeks — provides the foundational classified-vulnerability evidence the directive responded to.
The competitive read against the 100+ cybersecurity experts letter arguing for reversal is that defensive-cybersecurity-tool access policy has structural tension. Frontier-AI capability that can breach classified systems in hours is exactly the capability defenders need to test their own systems against. Restricting access to U.S. citizens only restricts both attacker AND defender access — the policy tradeoff doesn't favor defenders unilaterally. OpenAI's Patch the Planet program + Anthropic Glasswing represent the defensive-cyber-product layer that this policy tension affects directly.
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