President Donald Trump on Friday reversed his decision to eliminate the “de minimis” loophole that allowed packages from China valued at under $800 to be processed without customs duties or tariffs, a component of the 10% tariff on Chinese imports that took effect Tuesday—a move that threatened discount Chinese retailers Temu and Shein.

Mr Trump’s new trade barriers will be a blow not only to American consumers, but also to the e-commerce companies that have cashed in on the de minimis exemption. Shein, a Chinese apparel group whose largest market is America,