China has informed SoftBank that it will not approve the Japanese conglomerate’s planned $5.4 billion acquisition of the robotics division of Swiss engineering firm ABB, according to multiple sources. China’s National Development and Reform Commission (NDRC), a powerful state planner, reportedly communicated the decision. The move is a major setback for SoftBank CEO Masayoshi Son’s ambition to expand into physical artificial intelligence.

China is the largest market for ABB’s robotics business, which has extensive manufacturing operations there, including a major factory in Shanghai. Beijing’s reported concerns focused on transferring assets developed in China to a Japanese company and the risk that robotics data could be sent overseas and used to train AI models.

SoftBank secured China’s competition approval in February, but the deal later faced a more stringent foreign investment security review.