Open-weight models are AI systems whose underlying "weights"—the billions of numbers that decide how a model responds—get published for free. Anyone can download them, run them on their own servers, and modify them. That's the opposite of closed models like OpenAI’s GPT or Anthropic’s Claude, which only run through a company's paid app or API.
The letter draws a direct line to the 1980s open-source software movement, arguing AI has reached a similar fork in the road. "Our AI leadership will be judged not by one frontier AI model, but by whether the United States builds a strong, open ecosystem that diffuses into every sector," the letter reads.
Nvidia CEO Jensen Huang shared the letter in his first-ever post on X. "AI will transform every industry, power every company, and be built by every country," he wrote. "Open models strengthen safety and cybersecurity, accelerate innovation and diffusion, and enable sovereignty." Microsoft's Satya Nadella posted it too, calling open models "essential to a healthy AI ecosystem" while protecting national security.
AI will transform every industry, power every company, and be built by every country.
The letter pushes back on that framing directly: "Openness may be one of the most important paths to AI safety and security." It also draws a line around distillation, the practice of training one model using another's outputs, calling it a legitimate technique rather than theft that deserves "targeted legal and commercial frameworks" instead of blanket bans.
“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,” the letter reads.
“By contrast, unlawful efforts to extract value from closed models raise legitimate concerns. Those concerns should be addressed through targeted legal and commercial frameworks rather than sweeping restrictions on techniques that play an important role in AI innovation.”
Notably absent from the 25 signatories: OpenAI and Anthropic, the two closed-model labs both reportedly preparing IPOs this year.
