The seemingly never-ending trade dispute between China and the US often seems like a game of snakes and ladders. Last week China signaled a breakthrough on a quarrel that has roiled economies around the world – only for the Trump administration to issue a denial. The sticking point, for some, appears to be the US opioid crisis.

America is in the grip of its worst drugs crisis in a generation. About 130 people die each day in the US from opioid-related overdoses and many – including Donald Trump – blame imports of cheap drugs from China.

Beijing’s acknowledgment of the issue’s importance to the US came on Thursday when China’s National Narcotics Control Commission held a press conference about a fentanyl smuggling case cracked in a joint operation between US and Chinese authorities.

The trial, which culminated in three Chinese nationals being sentenced to maximum punishments for smuggling fentanyl to the US and six others sentenced for up to two years, is one of China’s highest-profile cases aimed at curbing the illicit flow of opioids.

Chinese-produced fentanyl or Chinese-produced ingredients for the drug have been repeatedly blamed by Trump for the soaring number of US opioid-related deaths.

According to the US Centers for Disease Control and Prevention, more than 28,000 synthetic opioid-related overdose deaths were recorded in 2017 alone, and fentanyl-laced pills have been blamed for several high-profile deaths, including the musicians Prince and Tom Petty.

The emergence of fentanyl as an underlying reason for trade tensions is not new, say observers of the on-again, off-again negotiations, but it has gained importance as a political issue as Trump heads into an election year.

“Fentanyl matters a lot in US politics, because it could be politically devastating among suburban housewives in swing states if fentanyl-related deaths are blamed on Trump’s political inaction on the issue,” said Derek Scissors, a scholar with the pro-market American Enterprise Institute.

Fentanyl was implicated in the death of the musician Tom Petty. Photograph: Rex/Shutterstock

“The administration knows they have to neutralize fentanyl as a political issue to make a deal with China, and the Chinese have figured out they have to cooperate on this if they want a deal with the US,” Scissors said. “There has to be progress or a deal can’t hold together.”

US pressure on China to crack down on fentanyl first emerged in trade negotiations in November 2017 when Trump warned the Chinese leader Xi Jinping, on a trip to Beijing, that he would make stopping the “flood of cheap and deadly” fentanyl “manufactured in China” a “top priority”.

“A special emphasis will be placed on the new phenomenon – fentanyl – destroying lives by the millions. We’re going to be focusing on it very strongly, the president and myself,” Trump said at the time.

But it was not until the G20 summit of world leaders in Buenos Aires last year, where Trump pressed Xi on the issue at a steak dinner that capped the conference, that China agreed to list fentanyl and its derivatives as a controlled substance, according to CNN.

That move came after the White House reportedly sent a copy to Xi of a Los Angeles Times article headlined “Fentanyl smuggled from China is killing thousands of Americans” with “you have to help us with this” scribbled on it.

In August, Trump again accused Xi of failing to crack down on the flow of Chinese-produced fentanyl.

According to the Drug Enforcement Agency, China is responsible for the precursor chemicals for fentanyl, while most of the production is now through Mexico, a marked shift from recent years when shipments went largely unchecked from China to the US.

In congressional testimony last year, the DEA deputy chief, Paul Knierim, described China as “one of the world’s top producers of the precursor chemicals used to manufacture methamphetamine and fentanyl, as well as the chemicals used to process heroin and cocaine.

“Combating illicit fentanyl is a top priority of this administration,” Knierim said, welcoming “positive actions being taken by the Chinese government over the last year. Their actions are steps in the right direction, but more can be done.”

While US opioid-related deaths, estimated at 400,000 since 2000, appear to have peaked, China’s agreement to put controls on all fentanyl substances came only after years of bilateral dialog, according to the DEA.

“It is a very significant step for them and we appreciate China’s efforts,” a DEA spokeswoman, Katherine Pfaff, told the Guardian. But the effectiveness of China’s crackdown is unclear.

“Based on past actions, whenever China has put controls into place we have seen a difference in what is coming into the US from China, or sourced from China,” Pfaff added.

While the smuggling trial, which was broadcast on television, is widely held to be a signal that China is prepared to go some way to meet Trump’s demands, Beijing maintains it is not responsible for the fentanyl aspect of the US opioid epidemic.

In the past, Beijing has described the US holding China responsible for fentanyl production as political “fantasy”.

That position was repeated on Thursday when Yu Haibing, deputy secretary general of the China National Narcotics Control Commission, said: “China’s control of fentanyl has become more strict, but the number of deaths in the US from fentanyl have risen. This shows that China is not the source of the problem,“ said Yu, reported Bloomberg.

Still, the trial was heralded as an important step by US authorities.

“As the success of the joint investigation demonstrates, Chinese and American investigators have the capacity to collaborate across international borders,” said Austin Moore, an attache with the Department of Homeland Security in Beijing, said at a briefing.

The issue of China and fentanyl is likely to remain tense for the administration. “Trump already said China is going to help us with this. If they don’t, Trump is stuck,” said Scissors. “The trial was a gesture of good faith. Now it’s up to the US to reciprocate.”