BEIJING (Reuters) — China’s main ports will step up quarantine checks on imports of apples and logs from the United States, and shipments found carrying disease or rot could be returned or destroyed, the Chinese customs agency said on Monday.

Reuters reported last week that the main Chinese ports of entry have ramped up checks on fresh fruit imports from the United States, which could delay shipments from U.S. growers already dealing with higher tariffs as China-U.S. trade ties sour.

“Recently, pests were detected in apples and logs imported from the United States at the ports of Shanghai, Shenzhen, Qingdao, Xiamen, and others,” the Chinese General Administration of Customs said in a statement posted on its website.

If apples or logs are suspected of carrying pests, samples will be sent to laboratories for inspections, and while the tests are underway goods will not be allowed to pass through customs.

Previously, customs officers in China had let shipments through while they conducted sample checks.

The measure was announced days after a U.S. delegation led by Treasury Secretary Steven Mnuchin visited Beijing for two days of talks aimed at easing trade tensions between the world’s two biggest economies.

U.S. President Donald Trump has threatened to impose tariffs on up to $150 billion in Chinese goods over allegations of intellectual property theft.

Fruits were among 128 U.S. goods that China slapped with more expensive import tariffs early last month in retaliation for U.S. levies on Chinese steel and aluminum.