The issue brief examines the evolution of China’s role in global illicit fentanyl trade. China placed all forms of fentanyl and its analogues on a regulatory schedule in 2019, but the U.S. Drug Enforcement Administration (DEA) assesses China remains the primary country of origin for illicit fentanyl and fentanyl-related substances trafficked in the United States. While Mexican drug cartels have always been a critical node for smuggling illicit fentanyl into the United States, this brief finds that the links between Chinese and Mexican actors in the fentanyl trade has grown in complexity, including the development of sophisticated money laundering operations. Finally, the brief concludes that while cooperation between the United States and China remains limited, there are opportunities for the United States to work with other countries on counternarcotic enforcement.