Is the China-US fentanyl pipeline really responsible for the US opioid crisis?

Packets of fentanyl and methamphetamine that US Customs and Border Protection says it seized from a truck crossing into Arizona from Mexico. Photograph: Reuters

Donald Trump has imposed tariffs of 10% on Chinese imports, framing the move as a way to pressure China into taking action on fentanyl.

The White House said on Tuesday: “Chinese officials have failed to take the actions necessary to stem the flow of precursor chemicals to known criminal cartels and shut down money laundering by transnational criminal organisations.”