Tens of thousands of Americans have received mysterious seed shipments in the past few months. Most have been postmarked as coming from China and have often been falsely labeled as another product. At least some of them were potentially harmful to US agriculture, including noxious weeds, plant diseases and even pests.

The US is working with China to track down the seed sources. This isn’t necessarily an attack — one main theory suggests the seeds are part of a “brushing” scam where vendors pay people (“brushers”) to order cheap products and write bogus reviews to spur sales. Amazon maintained that seed deliveries from its site were real orders delayed due to the COVID-19 pandemic, but it’s investigating possible links between its site, the packages, and possible brushing.

Amazon’s crackdown might not amount to much if the seed mailers are using other services. Even so, this reflects the company’s increasingly active response to dodgy products and orders. It doesn’t want to be held responsible for problematic shipments, and it’s apparently willing to lose potential sales rather than risk future incidents.