Three competing open letters in five days split the industry.

Willison's August 2 roundup lays out "Open Weights and American AI Leadership" (July 24, Microsoft-shepherded, now 235 signatory companies including NVIDIA, Amazon, Y Combinator, the Linux Foundation, and OpenAI after initially abstaining); Anthropic's separate July 27 rebuttal from Dario Amodei; and "Pacing the Frontier" (July 28), which Amodei and Jack Clark did sign. The open-weights letter grew from ~25 signatories to 50 within a day to 235 by August 2, and explicitly endorses distillation as "a widely used technique for model improvement"; the exact practice Amodei wants cracked down on at "industrial scale." Practical read: no US ban on open-weight models is coming, but a compute-threshold safety-testing regime applying to open and closed models alike now has backing from the one lab that stayed off the coalition letter.