BEIJING (AP):- A Chinese province has launched a crackdown on the fentanyl trade — a contentious issue in U.S.-China relations — arresting seven people and shutting down more than 200 websites in recent months, state media reported Thursday.

The announcement came shortly after U.S. President Donald Trump said he would postpone a highly anticipated trip to China because of the Iran War. Trump has used tariffs to try to pressure China to do more to stem the export of fentanyl precursors — the chemical ingredients that go into the synthetic opioid blamed for tens of thousands of overdose deaths annually in the U.S.

The Hubei Daily News said in an online report that a fentanyl precursor task force established in December had investigated 22 cases in Hubei province through February. Besides the seven arrested, a dozen other people have been subjected to “coercive measures,” which can include being summoned or detained. Four companies have been penalized, the newspaper said.

The official Xinhua News Agency issued a similar report. It said the task force had been set up to follow a directive from China’s Ministry of Public Security. The operation followed an agreement by China at the end of October to take steps to stop the precursor trade in return for a halving of the fentanyl-related tariff on U.S. imports from China to 10%.

In one case, information from the U.S. Drug Enforcement Agency helped police in Wuhan, the provincial capital, discover that a company was selling precursor chemicals as well as stimulants, the Hubei Daily News said. The person who controls the company was arrested in early December with the cooperation of police in another province, Shandong, the newspaper said.

Two people have been arrested in another case in which the suspects are alleged to have set up shell companies for the sale of drugs and chemicals that could be used to manufacture drugs overseas, the report said.

Trump, citing the fentanyl issue, put a 10% tariff on China soon after he took office last year and later raised it to 20%. He layered additional tariffs on China and other countries starting in April. China countered with tariffs of its own in an escalating back and forth. The two sides announced a one-year truce and the agreement to roll back the fentanyl-specific tariff to 10% after Trump met Chinese leader Xi Jinping in South Korea at the end of October.

Plans were underway for a second in-person meeting in Beijing around the beginning of next month when Trump said earlier this week that his administration was working with China to reschedule the visit and that he would go in about five or six weeks, which would be late April.