As Donald Trump travels to Beijing this week, fentanyl remains a point of acrimony in bilateral relations. Yet there are growing signs that the US fentanyl crisis has turned a corner, and some experts believe that interventions in China have played a key role.
Supply Shock from China
“There was a supply shock: the purity of fentanyl fell,” said Keith Humphreys, a professor at Stanford University. “The question is why was there a supply shock. And most indicators point to China.”
On returning to the White House, Trump made fentanyl a foreign policy priority, designating criminal groups as foreign terrorist organisations and slapping tariffs on countries involved in its supply chain, including China, the main source of fentanyl precursors.
But by the summer of 2023, during the Biden administration, overdose deaths at the national level had already begun to fall. By November 2025, they were down by more than a third.
Evidence of Disruption
Investigators are still unpicking the factors behind the fall. One theory, put forward by Humphreys and his co-authors in a recent study published by Science, links it to interventions in China that may have caused a long-lasting disruption to the fentanyl supply chain.
The authors point to a dramatic fall in the purity of fentanyl being seized by US law enforcement from May 2023 to the end of 2024, which correlates with the fall in overdose deaths. A similar fall in purity occurred in Canada, a distinct fentanyl market, suggesting the cause might originate where both countries source their precursors: China.
Reports from 2024 of cartel cooks struggling to source precursors and the appearance of new adulterants in fentanyl on US streets support the idea that the flow of precursors was disrupted.
Caution and Caveats
There are big caveats. It is difficult to pinpoint which of China’s self-reported interventions might be responsible, and it is unclear that the fall in purity caused the fall in overdose deaths.
Nonetheless, Liu Pengyu, spokesperson at the Chinese embassy in Washington, said China was glad to see fentanyl overdose deaths had decreased and noted that the US government’s 2025 National Drug Threat Assessment “implies that Chinese government efforts have made [a] contribution to addressing the fentanyl problem in the US”.
Henrietta Levin, former director for China on Biden’s National Security Council, said her former colleagues saw the Science paper as showing that their pressure on China had worked. “I think China could have done more,” said Levin. “But what they did do mattered.”
Further Interventions
Further supply-side interventions are likely to be on the agenda at this week’s summit. Ideally, said Levin, these would include China changing laws to make it easier to prosecute drug trafficking and more action from its commerce ministry to control the behaviour of chemical companies.
“A lot of this comes down to enforcement,” said Levin. “China announced export controls [on various fentanyl precursors], and that’s important. But Chinese chemical companies are gauging how serious the government is about actually enforcing those restrictions.”
Historical Precedent
Yet history shows that, so long as demand exists, supply shocks are always temporary and can have unpredictable effects, even making things worse. After China put a blanket ban on fentanyl in 2019, the supply chain evolved to loop Mexico’s cartels in, who began importing precursors from China and trafficking the finished product over the US-Mexico border, almost entirely replacing their previous trade in heroin.
“There’s a kind of myopia here,” said Nabarun Dasgupta, director of the University of North Carolina’s opioid data lab. “That time, the geopolitics of it backfired.”
