The U.S., where fentanyl abuse has been a major cause of death, has pushed China for deeper law enforcement cooperation, including tackling illicit finance, arrests of rogue chemists and raids of labs involved in the production of precursors.

U.S. President Donald Trump threw a curve ball at China by linking the fentanyl issue to his tariffs on imports. The Chinese government is swinging back. First it issued a report detailing its efforts to control the illegal trade in fentanyl,