What is Kimi K3, China’s first open AI model to reach 2.8 trillion parameters?

Chinese AI firm Moonshot AI announced its Kimi K3 model, an "open model" with 2.8 trillion parameters and a 1-million-token context window, claiming it's the world's first open 3T-class model. While it trails top US models like Claude Fable 5 and GPT 5.6 Sol, it outperforms older US rivals and is designed for frontier intelligence. US AI companies have raised concerns about Chinese firms releasing competitive models at lower rates and suspect data distillation.