For decades, Apple has navigated an escalating series of challenges in China, from fake stores and factory protests to tightening censorship and app rules. Now, the iPhone maker risks getting dragged into the most volatile issue in U.S.-China relations: the future of Taiwan.

On Sunday, Taiwanese contract manufacturer Foxconn Technology—one of Apple’s largest suppliers—said it is cooperating with Chinese authorities after state media reported China had opened tax and land-use probes into the company. The investigations come as Foxconn’s billionaire founder Terry Gou pursues a bid for the Taiwan presidency.