China has halted exports for a range of critical rare earth minerals and magnets, and has ordered its domestic airlines to stop taking deliveries of Boeing planes.

China first announced the export restrictions on minerals and magnets on April 4, requiring all companies to get special permission from the government to ship the products out of the country, but has barely started setting up a system for issuing the licenses. Although the crackdown isn't limited to the U.S., the move is a direct response to the 145% tariffs imposed by the Trump administration against Chinese exports, according to The New York Times. 

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China produces more than 90% of the world's supply of refined magnet rare earth elements, used as components for semiconductors, planes, drones, and even missiles. The magnets produced from China's rare earth minerals are also essential for a variety of car parts, including batteries, spark plugs, headlights and steering systems. Should the export restrictions persist, U.S. companies — many of which don't keep existing stockpiles of the pricey materials — could soon face manufacturing disruptions across a variety of sectors.

China took aim at the U.S. aviation industry on April 15 as well, with Bloomberg reporting that the country had instructed its carriers to no longer accept Boeing jets, and to stop buying airplane components from any U.S. companies. Boeing had previously been scheduled to ship 10 737 Max planes to Chinese airlines, although a small portion may still be allowed to enter China in the weeks ahead, given that payment and delivery paperwork for a handful of jets might have already been completed.