This study examines how external shocks spread internationally to firms in third countries through global value chains, focusing on the impact of the US–China trade war on Japanese firms. Firms in Japan that heavily rely on exports to China experienced a 7.5% decline in exports, with non-MNEs showing the greatest impact. Japanese MNE affiliates in China experienced a 34% decrease in exports to the United States, although the overall impact was limited as only a few subsidiaries were involved in US-bound exports. Although, in China, local sales by Japanese affiliates declined by 25%, many of these firms offset this decrease by increasing their exports to Japan and other Asian markets. The dispute also led to a slight reduction in procurement from parent companies in Japan, although this effect was minor. In sum, non-MNE exporters in Japan and MNE affiliates reliant on North American exports have been the most affected by the trade war.