the us government ordered anthropic to block foreign nationals from accessing its two most advanced models, fable 5 and mythos 5, citing national security. the shutdown order came four days after fable 5 — described as the most powerful publicly released model — went live on june 9, so a frontier system was published and then forcibly walled off within a week. this is the first time a public frontier model has been pulled from global access by a state for export-control reasons.