Automotive industry groups are increasingly worried about a rare earth shortage.

Several European auto supplier plants and production lines have already been shut down due to China’s recent export controls, according to Europe’s auto supplier association CLEPA, with the group warning of more outages as inventories deplete.

Germany’s car industry and auto executives have also sounded the alarm, saying the highly globalized sector is acutely vulnerable to further supply chain disruption.

China’s Ministry of Commerce in early April imposed export restrictions on several rare earth elements and magnets widely used in the automotive, defense and energy sectors. The curbs came as part of a response to U.S. President Donald Trump’s tariff increase on Beijing’s products.

Some of the affected rare earth elements are vital components to the production of both combustion engines and electric vehicles.