AI News Brief: Leading AI chipmakers and open-source model advocates have jointly spoken out against overly restrictive US government measures targeting ‘open-weight’ AI models. Multiple AI companies including Hugging Face, Meta, Microsoft, Mistral, and Nvidia have signed an open letter urging policymakers not to impose ‘premature broad restrictions’ on open-weight models. The letter comes as Washington deliberates how to respond to allegations that Chinese AI labs stole IP from US counterparts, and amid growing concerns over China’s rising AI capabilities. The letter does not mention China by name, but its timing coincides with reports that the Trump administration is considering an outright ban on Chinese open-weight models, and potentially sanctions on Chinese AI companies; the White House has also accused Moonshot AI of using distillation on Anthropic’s Fable model to train its newly released, impressive Kimi K3 model. The open letter emphasizes that distillation is a common technique widely used for model improvement, evaluation, and validation, rooted in the ‘standing on the shoulders of giants’ innovation tradition from the open-source software movement. Policymakers should not conflate legitimate model development techniques with improper theft; illegal appropriation of closed-model value should be handled through targeted legal and commercial frameworks, not blanket restrictions on key innovation techniques like distillation. Replit CEO Amjad Masad, one of the signatories, told TechCrunch that ‘banning Chinese open models is equivalent to banning the entire open-model ecosystem,’ citing Thinking Machines Lab’s new open model Inkling—which was trained with help from Moonshot’s Kimi 2.5—as an example of how interconnected the ecosystem is. The open letter also rebuts the argument that ‘open-weight models are inherently dangerous and could be used for cyberattacks,’ arguing that defenders need equally capable models to detect, simulate, and respond to emerging threats; open models actually expand defensive capabilities, improve transparency, and let more teams find and patch vulnerabilities.