2026-08-02 04:16 UTCOriginal source2 min readUpdated: 2026-08-02 05:05 UTC

The wave of open letters about AI development

Microsoft shepherded an open letter signed by 235 AI-adjacent companies defending open-weight models; Anthropic declined to sign and published its own stance; then 1,324 frontier AI employees called on the US government to support international efforts to deliberately pace automated AI development.

SourceSimon Willison's Weblog

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Key points

Microsoft-led open letter with 235 signatories argues against banning open-weight models on safety grounds and supports distillation.
Anthropic was notably absent, with Dario Amodei highlighting risks of authoritarian misuse and industrial-scale distillation attacks.
Pacing the Frontier, signed by 1,324 frontier AI employees, asks the US government to support international governance tools for automated AI R&D.
Examples like Anthropic's 80% Claude Code usage, OpenAI's Sol cost cuts, and Kimi K3's custom chip illustrate accelerating automated AI progress.

Why it matters

This matters because microsoft-led open letter with 235 signatories argues against banning open-weight models on safety grounds and supports distillation.

Technical impact

May affect model selection, inference cost, product capability, and evaluation benchmarks.

This panel is AI-generated and reviewed for accuracy.

Open letters about AI development

Simon Willison’s Weblog

2nd August 2026

Open letters about AI development

I wrote this summary of the past few weeks of open letters as a section of my sponsors-only newsletter but I've decided to share it here as well.

Open Weights and American AI Leadership was shepherded by Microsoft, dated July 24th, and signed by 235 AI-adjacent companies including NVIDIA, Amazon, Y Combinator, The Linux Foundation and (a later signer) OpenAI.

It's clearly an argument designed to counter any instincts by the current US government to ban or limit open weight models over "safety" concerns - a reasonable consideration given what happened to Claude Fable 5!

Relying solely on closed models is not inherently safe: they can be breached, misused, or fail in ways that outsiders cannot detect. And concentrating advanced AI capabilities behind a small number of closed models compounds that risk. It results in a small number of single points of failure, weakens competition, and leaves critical technology in the hands of a few providers. Open weight models, on the other hand, allow a broad community of researchers and developers to examine their behavior, identify vulnerabilities, develop safeguards, and improve them over time.

The one surprising note in the letter is that it comes out in support of distillation, where models train on output from other models:

In shaping this ecosystem, policymakers should be careful not to conflate legitimate model-development techniques with misappropriation. Distillation, or the practice of using one model’s outputs to help train or improve another, is a widely used technique for model improvement, evaluation, and validation. It reflects a long tradition of learning from, building upon, and improving existing technologies, a tradition that has helped drive innovation since the rise of the open-source software movement.

Notably absent from the signatures: Anthropic, who published their own response Our position on open-weights models three days later. CEO Dario Amodei doubled down on the risk of authoritarian governments building "AI models that are more powerful than those built by the US", and models being "misused to carry out cyberattacks or biological attacks", and called for "a crack down on industrial-scale distillation operations", while also stating that "Anthropic has never advocated for a ban on open-weights models".

Then on July 28th Pacing the Frontier was published, featuring signatures from "1,324 employees of frontier AI companies" - with names like Jakub Pachocki (Chief Scientist, OpenAI), Ilya Sutskever (Safe Superintelligence Inc, previously OpenAI), Dario Amodei (Anthropic), Jack Clark (Anthropic) and more. Their core message:

We request that the U.S. government support an international effort to develop the technical and governance tools needed to deliberately pace the frontier of automated AI development.

Their concern is intense competitive pressure combined with accelerated AI progress caused by automated AI research - and given that Anthropic produce 80% of their code with Claude Code, OpenAI had Sol reduce their end-to-end serving costs by 20%, and Kimi K3 designed a chip to serve a nano model built on its own architecture, you can see why people are taking that risk more seriously right now.