Peter Girnus 🦅@gothburz
The letter reached Dario Amodei Friday night, around 9:47, and by the time I left the building the sequence was already closed.
I am the Deputy who ran the interagency process on Claude Mythos 5 / Fable 5, and it took an afternoon. Andy Jassy had told Scott Bessent that Amazon's own researchers used Claude Fable 5 to pull cyberattack-useful material out of the model. Bessent called me. I called Commerce. By Saturday morning, Fable 5 and Mythos 5 were dark for every user on earth.
People ask why I trusted Amazon. Amazon put roughly eight billion dollars into Anthropic, a stake the cap table now carries near seventy-four billion, and a man does not call a Cabinet secretary's cell on a Friday to put a number like that at risk unless he has already decided how the call should end. Jassy decided. Seventy-four billion at risk. That was the number I weighted.
Then I picked the instrument. A safety review takes weeks, because you have to convene the reviewers, argue the capability, survive the dissents, and stand behind a written finding that someone can later prove wrong. An export-control order takes a signature. I treated Fable 5 the way we treat an advanced chip, put the weights on the same control list as the silicon they run on, and because showing those weights to a foreign national inside our own building counts as an export, I barred foreign-national access worldwide, including Anthropic's own foreign-national staff, overnight. That same week we cleared the advanced chips themselves for sale to China. The silicon shipped. The model a Chinese national could touch on US soil went dark. Export control does not require you to be right by Monday. That is why I used it.
Then the collateral, and I will be precise, because it is what closed the file for me. The ban cut off AWS, Amazon's own cloud, the one Anthropic had pledged about a $100 billion dollars to run on, which means the partner who reported the threat severed his own data centers to land the finding. He took the loss himself. That settled it for me.
One of Anthropic's own engineers, a green-card holder, lost access Saturday morning to the model she had spent two years building. Her code is still inside it. She can no longer open the thing she made. I noted that the rule was working as written.
I never ordered the models pulled. The finding was briefed to us out loud. Nothing on the record, no exhibit, no written determination, just Sacks describing the source as a highly credible trusted partner, and credible was enough. My ask to Dario was three words. Fix it or pull it. I put it on a recorded line so the choice would be his on the record, and when he would not accept my read he pulled both Fable 5 and Mythos 5 himself, for every user on earth. I signed nothing that made him.
Anthropic came back with a rebuttal. The jailbreak was narrow. OpenAI had shipped the same capability in GPT-5.5 that same month, and the letter named no specific national-security detail. All true. GPT-5.5 had no investor with a reason to call, so GPT-5.5 got no letter.
Before this weekend, no frontier model had ever been pulled from the public by this government. Now one has, and the procedure has been tested in production.
The list had no names. Now it has mine.
