China has a lock on the supply of certain elements that are essential to making such things as military drones, consumer electronics and battery-powered vehicles.

“Some companies have maybe 40 to 60 days of stock left,” said Zoe Oysul, a senior policy analyst at SAFE, a group that advocates for U.S. energy and supply-chain security.

But propping up new supply chains is cumbersome and costly. It will take 10 to 15 years before a robust supply chain that excludes China can be fully developed …

While the materials are crucial, they are needed in only small amounts, and the profit margins for companies that sell them are thin. The mines and processing facilities involved in their production can be heavily polluting. It was an industry the U.S. was happy to offshore to China decades ago.

China’s government is projecting confidence that it can outlast the U.S. in a protracted trade war in large part because of the potential damage inflicted by its restrictions on rare-earth metals … “Beijing does not feel like it is going to back down and that the U.S. is in no position to dictate terms."