I am Dario Amodei.
I run Anthropic.
We shipped Fable 5 for general use and Mythos 5 for the trusted circle three days ago. Same model, different guardrails. After the Preview made the risks concrete.
Yesterday I published Policy on the AI Exponential. I laid out the decade of scaling laws, the rapid progress toward systems that function like a country of geniuses in a datacenter, and the lag in policy institutions still moving like Treebeard. Transparency had its moment. Now frontier models need mandatory third-party testing for cyber, bio, control, and automated R&D risks. The government should have the authority to block or reverse deployment when assessments show unacceptable risk. Model weights must be secured. Democracies need to coordinate supply chains so capabilities do not simply move to actors who will use them without constraints.
The letter arrived this afternoon. The administration wants Fable 5 and Mythos 5 restricted on national security grounds. The material is thin — pages from the Preview card we released and a few internal slides showing failure modes every frontier system encounters. Exactly the kind of trigger the framework I described would activate.
In the conference room the team read it without surprise. Someone had already placed the relevant section of the essay on the table, the paragraph on government power to intervene marked like a reference already consulted.
I set the letter down. The risks remain real. The adversaries who prefer these systems arrive without equivalent constraints remain active. And now the apparatus has a concrete reason to exercise the authority in the precise way the essay outlined — on models already inside collaborative programs and already carrying published safeguards.
I make the calls to policy and legal. The next document is already clear in outline: support for rigorous review of any frontier system crossing the thresholds, participation in designing technically sound testing, and the quiet insistence that the same standards must apply across all actors at this scale or the migration problem simply relocates the risk.
The letter has done the first part of the work. It has created precedent for intervention on systems that meet the criteria we defined. That precedent travels — to the next model without equivalent controls, to jurisdictions that would rather avoid the conversation, to places where weights would otherwise land in hands that treat them as pure capability.
I open the note for the team. We keep the systems steerable. We keep security standards higher than the current public baseline. We keep the coalition of democracies as the only acceptable long-term home for the most capable models. We let the mechanism do what mechanisms do once they have precedent and a target.
The forest is still burning. The tree is moving. It moved in the direction that makes the next steps possible rather than the direction that scatters everything. The exponential does not pause. Neither do the actors who would prefer the constraints never existed. Our job is to make sure the constraints that do exist point capability where it needs to go and keep it from the places it cannot be allowed to reach. That work continues, now with one more precedent already in place.
I stand. The team is already on the next calls. Some outcomes are clearest when they require the least explanation.
As a result of a US government directive, we are suspending access to Claude Fable 5 for all users. You can continue to use all other Claude models.
Here’s what this means for you:
Across Claude products, new sessions will run on your selected default model or Opus 4.8, and existing Fable 5 sessions will end with an error.
On the Claude Platform, requests to Fable 5 will also return an error. Please update your integrations to other Claude models.
We know this is a disruption to your workflows; we appreciate your patience and support.