A synthetic opioid at the heart of America and China's uneasy trade-war truce. The drug has killed more than 300,000 Americans since 2020 and related overdoses are the leading cause of death for Americans aged 18-44.
China's massive chemicals industry accounts for about 40% of global chemicals production. Its loosely regulated factories can easily manufacture both fentanyl (which is also used for legitimate medical purposes) and the precursors needed to make it. China's underground financial networks help launder money for gangs: more than $150bn in illicit proceeds moves through China each year, according to American officials. China itself does not appear to have a big domestic problem with synthetic opioids.
In 2019, under pressure from Donald Trump's first administration, a Chinese crackdown on illegal production disrupted fentanyl supplies. The street price of the drug in America rose for several months, and 20-25% fewer people died of overdoses in that period, according to a study by the Peterson Institute for International Economics. The industry adapted, however: Chinese factories largely stopped making illegal fentanyl but continued to churn out precursors, which are typically sent to Mexico (and, to a much lesser extent, Canada) to be turned into the final product by gangs before being smuggled over the border.
America has repeatedly asked China to tackle the trade in precursors, which are hard to track because many are also used perfectly legally. China has tightened controls on more chemicals (or "scheduled" them), shut down certain companies, made arrests and, according to officials, blocked or removed over 140,000 illegal advertisements. A report by America's State Department in September 2025 found that China "continued to fall short of the decisive measures needed" and that online platforms were openly selling precursors to criminals.
A big loophole relates to precursors used for so many legal purposes that it is not practical to schedule them. American law still allows those who sell them to criminals to be prosecuted, but Chinese law is fuzzier, according to Vanda Felbab-Brown of the Brookings Institution.
China tends to ease up on fentanyl co-operation whenever the bilateral relationship sours. In 2020 it dialled back after America imposed sanctions on a government forensic-science institute for alleged links with the repression of the Uyghurs. In 2022 China stopped helping entirely after Nancy Pelosi, then speaker of the House of Representatives, visited Taiwan. Joint work did not restart until President Joe Biden agreed to lift the sanctions at a meeting with Xi Jinping in late 2023. Efforts were interrupted again after Trump announced new tariffs in 2025. Henrietta Levin, a former director for China on Biden's National Security Council, said: "China sees action against fentanyl as leverage. They don't intend to do more than what is politically advantageous to them at any particular moment."
As part of the October 2025 trade deal, Trump agreed to halve a 20% tariff imposed over fentanyl. Xi "is going to work very hard to stop the death", Trump told journalists. On November 10th 2025, after a visit to Beijing by FBI director Kash Patel, officials from China's public-security ministry released a list of 13 chemical precursors that will require extra approvals before they can be sold to customers in America, Canada and Mexico. China's counter-narcotics authority issued a notice "reminding" exporters of "legal risks". A bilateral working group is being set up.
Overdose deaths have plummeted from nearly 85,000 in the year to June 2023 to 48,000 in the year to April 2025—"the most spectacular achievement we've had in terms of saving lives" in the opioid epidemic, according to researchers. About 70% of American overdose deaths involve fentanyl originating from China, formulated in Mexico and smuggled across the border.
A January 2026 article in Science by researchers from Stanford, the University of Maryland and other institutions attributes the decline primarily to a fentanyl supply shock rather than increased treatment access. Using DEA seizure data, the researchers showed that fentanyl powder and pills lost potency just as deaths fell—suggesting dealers practised "shrinkflation", reducing fentanyl content while maintaining prices. Fentanyl purity peaked in July 2023, then fell by more than half by end of 2024. Since the supply originates in China, the researchers hypothesise a supply-side change there caused the shock. Other researchers are sceptical, noting that the death rate fell before China and the United States increased co-operation in November 2023.
Three minutes' thought would suffice to find this out; but thought is irksome and three minutes is a long time.