The U.S. has been importing about three million parcels a day with little customs inspection, raising concerns about the ease of sending fentanyl.

Chinese packages under $800 were exempt from tariffs due to the "de minimis" exemption, now ended under new U.S. rules that came into effect Tuesday.

The move will likely have an impact on e-commerce platforms like Shein and Temu along with operators of drop shipping businesses.