China appears to have offered U.S. and European auto giants something of a reprieve over a rare earth shortage. China's Ministry of Commerce on Saturday said it was willing to establish a "green channel" for eligible rare earth export license applications to expedite the approval process to EU firms.

China's critical-mineral export controls have become a focus on Trump's criticism of Beijing, which he says has violated the truce reached last month to roll back tariffs and trade restrictions.

Each F-35 fighter jet contains roughly 900 pounds of rare earth materials, while submarines can require more than 9,000 pounds, the U.S. Department of Defense has concluded a stark reminder of how deeply integrated these elements have become in the machinery of modern defense.