With the release of its latest artificial-intelligence (AI) model, DeepSeek, an obscure Chinese firm, has laid waste to several years of American policy meant to hold back Chinese innovation—and, in the process, blown a hole in the valuations of companies from Nvidia, America’s AI chip champion, to Siemens Energy, a manufacturer of electrical equipment used in data centres. In demonstrating its ability to innovate around American export restrictions, DeepSeek has raised doubts as to whether access to piles of cutting-edge semiconductors and related equipment is as important as previously thought when it comes to training AI models.