FILE - A farmer cultivates his field near Farmingdale, Ill., Dec. 4, 2009, turning what remains of the plants back into the soil. A new study suggests no-till farming, in which fields are left alone between harvest and planting, releases less greenhouse gas.
FILE - A farmer cultivates his field near Farmingdale, Ill., Dec. 4, 2009.

The U.S. Agriculture Department issued a warning Monday urging all citizens who received unsolicited packages of seeds to turn the specimens over to the government for testing.

The mysterious packages allegedly originated from China and have appeared in mailboxes nationwide, prompting inquiries at both the state and federal level.

Local news outlets in Kentucky, New York, Idaho and Georgia have reported on the mysterious seeds, though the exact number of packets delivered is unknown.

Relations between China and the U.S. have rapidly deteriorated over the spring and summer months. The two economic powers are currently engaged in inflammatory disputes over the coronavirus, militancy in the South China Sea, Hong Kong and TikTok.

The USDA has refrained from blaming the Chinese government for the seeds, instead classifying them as a "brushing scam," in which people receive unsolicited items from a seller who then posts false customer reviews to boost sales.

At least two states have defined the phenomenon as “agricultural smuggling.”

Seeds are displayed at a garden center, April 14, 2020, in Nitro, W. Va.

U.S. officials fear the seeds could potentially destroy or severely harm agriculture and natural ecosystems, posing a threat to America’s food supply and environmental health.

Wang Wenbin, a spokesman for the Chinese Foreign Ministry, defended China’s postal service at a news briefing Tuesday, stating that they strictly adhere to agricultural regulations.

According to Weng, the postal service discovered falsified records pertaining to several of the packages in question and requested that the United States send the packages to China for investigation.

State officials said some packages were labeled as jewelry and may have contained Chinese writing.