China has strengthened controls on two chemicals that can be used to make fentanyl, its latest step in addressing an issue that has become tangled in its broader trade dispute with the United States.

中国加强了对两种可用于制造芬太尼的化学品的管控，这是为解决芬太尼问题采取的最新措施，这个问题已与中美更广泛的贸易争端纠缠在一起。

The Trump administration has accused Beijing of not doing enough to stem the flow of fentanyl, a powerful synthetic opioid, into the United States, where it kills tens of thousands of Americans each year. Earlier this year, the administration cited the issue as it imposed tariffs totaling 20 percent on Chinese goods.

特朗普政府此前指责中国政府没有采取足够措施，阻止芬太尼流入美国。芬太尼是一种强效合成阿片类药物，每年在美国导致数万人死亡。今年早些时候，美国政府以这一问题为由，对中国商品加征了总共20%的关税。

This week, six Chinese government agencies said they had added two chemicals, 4-piperidone and 1-Boc-4-piperidone, to a list of so-called precursor chemicals, or base ingredients, for fentanyl that would be more strictly controlled, according to a joint statement.

据中国六个政府部门本周发布的联合公告，中国已将两种化学品——4-哌啶酮和1-叔丁氧羰基-4-哌啶酮——列入所谓的芬太尼前体（即基本成分）清单，实施严格管制。

The move “demonstrates China’s sincerity in wanting to work with the United States on this issue,” said Yun Sun, the director of the China program at the Stimson Center, a Washington research institute.

此举“表明了中国在芬太尼问题上想与美国合作的诚意”，华盛顿研究机构史汀生中心的中国项目主任孙韵说。

The new restrictions, which take effect on July 20, were announced days after China’s minister of public security, Wang Xiaohong, met with David Perdue, the recently appointed U.S. ambassador to China, in Beijing last week to discuss efforts to fight drug trafficking.

新的管理措施将于7月20日生效。在宣布联合公告的几天前，中国公安部部长王小洪曾于上周在北京与新任美国驻华大使庞德伟(David Perdue)就禁毒执法进行了磋商。

The United States has accused Chinese producers of supplying drug cartels with the ingredients to make fentanyl, which the cartels smuggle into the United States.

美国指责中国的化工企业向贩毒集团提供芬太尼的原料，贩毒集团然后将芬太尼走私到美国。

China has maintained, however, that it is not responsible for America’s fentanyl crisis, which it says is rooted in the abuse of prescription painkillers and ineffective regulation in that country.

但中国则一直强调，美国芬太尼危机的根源在于国内滥用处方止痛药和监管不力，责任不在中国。

“We’ve repeatedly made it clear that fentanyl is the United States' problem, not China’s,” Guo Jiakun, a spokesman for China’s Foreign Ministry, said on Tuesday. “It’s the United States’ responsibility to solve the issue.”

“我们多次表明，芬太尼是美国的问题，不是中国的问题，”中国外交部发言人郭嘉昆周二说。“责任在美国自身。”

The tariffs imposed by the Trump administration over fentanyl are still in place, even though overall levies on Chinese goods came down to 55 percent from 145 percent or more in May, after the two countries agreed to a truce in their trade war.

两国同意暂停贸易战后，虽然对所有中国商品加征的最低145%的关税已在今年5月降至55%，但特朗普政府仍在收取与芬太尼问题有关的关税。

Chinese restrictions on its exports of crucial minerals recently threatened to derail that détente, but President Trump and China’s top leader, Xi Jinping, agreed to revive trade talks during a call this month. The two leaders also discussed the possibility of meeting in China.

中国前不久对关键矿产的出口实施限制措施，让缓和贸易战的进程受到威胁，但特朗普总统与中国最高领导人习近平已在本月通了电话，同意重启贸易谈判。两国领导人还讨论了在中国见面的可能性。

Wu Xinbo, the dean of the Institute of International Studies at Fudan University in Shanghai, said that China would like to host Mr. Trump, but that it depended on progress made on disputes over trade and issues like fentanyl.

上海复旦大学国际问题研究院院长吴心伯说，虽然中国愿意欢迎特朗普来访，但那取决于两国在贸易争端以及芬太尼等问题上所取得的进展。

Another option, Mr. Wu said, could be for the two leaders to meet on the sidelines of the annual Asia-Pacific Economic Cooperation summit in Seoul, which starts in late October. Mr. Xi usually attends the summit, and American presidents have typically done so, but neither leader has said whether he will participate in this one.

吴心伯表示，另一个可能性是两国领导人在今年10月底在首尔举行亚太经合组织年度峰会期间举行会晤。虽然习近平通常出席峰会，美国总统也历来如此，但两国领导人尚未表态是否参加今年的峰会。