China’s government is projecting confidence that it can outlast the United States in a protracted trade war in large part because of the potential damage inflicted by its restrictions on rare earth metals, said Eswar Prasad, a Cornell University economist who has spoken this week with Chinese finance officials.

China has been flexing its control over the mining and refining of minerals by adding metals essential for clean energy, chipmaking and defence to its export control list, disrupting global supply and sending prices soaring.