President Biden on Wednesday pressed Chinese leader Xi Jinping to crack down on Chinese companies that are helping produce fentanyl, a powerful drug that has killed hundreds of thousands of Americans.

A plan to curb China’s illicit fentanyl exports, and in particular the chemicals that can be combined to make the drug, was expected to be one of the most significant achievements for the United States from the Biden-Xi meeting, which It took place when leaders of Pacific nations gathered for an international conference in San Francisco.

A summary of the meeting published by China’s CCTV News said Biden and Xi had agreed to establish an anti-drug task force.

China is home to a thriving chemical industry that produces compounds that become pharmaceuticals, fragrances, textile dyes and fertilizers. Some of those same compounds can also be combined to create fentanyl, an opioid that can be 100 times more potent than morphine.

U.S. officials maintain that this vast chemical industry is playing a key role in the U.S. fentanyl crisis by supplying most of the materials used in illegal drug labs, including in Mexico, which is now the largest exporter of fentanyl to the United States. Joined.

The Chinese government denies that its country plays such a critical role and instead blames the United States for harboring a culture of drug use.

“All-out marketing by pharmaceutical companies, overprescribing by doctors, ineffective government crackdowns, and the negative implications of marijuana legalization are among the combination of factors behind a narcotics market in growth,” China’s Foreign Ministry said in a statement last year. .

U.S. officials say they have prevented more fentanyl from entering the United States in the past two years than in the previous five years combined. According to the Centers for Disease Control and Prevention, fentanyl and other synthetic opioids may have caused more than 77,000 overdose deaths in the United States between May 2022 and April 2023. The problem of fentanyl overdoses is particularly serious in San Francisco, where Mr. Biden and Xi are meeting.

Ian Johnson, senior fellow for China studies at the Council on Foreign Relations, said getting China to agree to do something about fentanyl will resonate more with the average American than the typical “outcomes” of international meetings.

“For Biden, it would be good to have to show the heart of America that relations with China are more than just an esoteric issue, but can actually bring something to ordinary people,” Johnson said at a briefing held by the council. last week. Republicans have made fentanyl-related deaths a centerpiece of their campaign against Biden and Democrats in the 2024 elections.

Still, given the difficulties in controlling an illicit industry, it is unclear to what extent a deal would stem the flow of fentanyl into the United States.

Roselyn Hsueh, an associate professor of political science at Temple University, said a deal between Biden and Xi could lead the Chinese central government to provide more oversight and invest more resources in inspection and monitoring. But she said Beijing had had difficulty in the past clamping down on fentanyl and its chemical precursors.

Before 2019, China was the primary source of fentanyl entering the United States, typically through mail and other commercial courier services. As part of trade talks with President Donald J. Trump, the Chinese government agreed in 2019 to ban the production, sale and export of all fentanyl-related drugs, except through special licenses.

But that resulted in Chinese companies diverting to Mexico and the emergence of India as a new production site, Ms. Hsueh said. The main source of US fentanyl was Mexican criminal organizations, which used Chinese-made components and Chinese money laundering services.

Today, online sales that mask the identities of sellers and buyers further complicate law enforcement. Regulation and enforcement of fentanyl and its chemical precursors remain “fragmented and decentralized” among Chinese local governments, industry associations and companies with vested interests in the chemicals trade, Ms. Hsueh said.

U.S. officials have said the problem is compounded because many of the ingredients used to make fentanyl are legal chemicals that can be used for legitimate purposes in other industries. The United States has issued sanctions against dozens of people in China and Hong Kong for their role in fentanyl trafficking. In September, Biden added China to the US list of the world’s top drug-producing countries, a move the Chinese government denounced as “a malicious smear.”

Last month, the U.S. Customs Department released an updated strategy to combat fentanyl and synthetic drugs, including through enhanced use of data and counterintelligence operations to track drug manufacturing and distribution networks, and target locations and suspicious recipients who demonstrate patterns of illicit activity.

“In my 30 years as a Customs officer, the trafficking of illicit synthetic drugs like fentanyl is one of the most difficult and daunting challenges I have ever seen,” said Troy Miller, Acting Commissioner of Customs and Border Protection.

U.S. officials believe China’s dominance as a chemical producer makes Beijing’s cooperation key to law enforcement. Administration officials, including Commerce Secretary Gina M. Raimondo, have raised the issue with senior Chinese officials during recent trips to China.

When six lawmakers, including Senator Chuck Schumer, the majority leader, had the opportunity to speak with Xi during a visit to China last month, the main issue they raised was not trade or military coordination or climate change, but the damage that fentanyl had caused in their home states.

“Everyone told stories, personal stories about how, you know, friends of ours, family members, died from fentanyl, and how this was a really important issue, and I think you could tell that it struck him, how deeply I felt about it. ”said Schumer, a Democrat from New York.

China’s fentanyl precursors have become a bipartisan issue in Congress, and the six senators who spoke with Xi were three Democrats and three Republicans.

“China needs to enforce laws that prevent the export of fentanyl precursors to international drug markets,” said Sen. Bill Cassidy, R-La.

Despite the magnitude of the problem, there is hope that greater coordination between the United States and China can improve the situation. Cooperation between the countries to prevent shipments of precursor chemicals stalled several years ago after the United States imposed sanctions on a Chinese government entity for its alleged involvement in human rights abuses in China’s westernmost region, Xinjiang.

That entity was located at the same address in Beijing as China’s National Narcotics Laboratory, which plays a key role in China’s law enforcement effort on drug-related chemicals.

Chinese officials deeply resent US sanctions on their institutions, and US officials have taken the position that, due to the risk of confusion between the two institutes in the same direction, neither institute can work with the United States.

China then expanded its position in August 2022, when it halted any counternarcotics coordination with the United States as one of a series of measures taken in response to a visit to Taiwan by Rep. Nancy Pelosi, then speaker of the House. Beijing claims Taiwan, a self-governing island democracy, as part of its territory.

Eileen Sullivan contributed reporting from Washington.