Ford CEO Jim Farley said that a rare earth minerals shortage is hurting production and caused the automaker to temporarily shut down one of its plants last month, according to an interview with Bloomberg TV. 

Rare earth minerals, which are a set of 17 metallic elements, are integral to automobile production, and enable features like windshield wipers, seat belts and speakers to function. About 90% of the U.S.’s rare earth minerals come from China, the world’s largest producer of rare earths, according to data from the Geological Survey.

China has leveraged its grip on rare earths and their widespread utility amid a trade war with the U.S. In April, Beijing announced greater export controls on the materials — a sticking point in tariff negotiations — along with other retaliatory trade measures. The controls require businesses to apply for a license to export rare earths, which U.S. automakers say they have been struggling to secure. 

Earlier this week, on June 11, following two days of discussions in London, U.S. and Chinese negotiators struck an agreement under which Beijing would resume regular exports of rare earths to the U.S.

“The centrality of rare earth export restrictions to the trade deal underscores the criticality of minerals to the U.S. economy as well as the severity of the chokehold Beijing holds on global supply chains,” policy experts from the Center for Strategic and International Studies wrote in a research note. 

“Hand-to-mouth”

Farley said the slowing flow of the critical minerals into the U.S. has presented a challenge for Ford. 

“It’s day to day,” he told Bloomberg TV Friday. “We have had to shut down factories. It’s hand-to-mouth right now.”

Ford did not immediately respond to CBS MoneyWatch’s request for comment. 

Ford Chief Financial Officer Sherry House addressed disruptions caused by new restrictions on rare earth minerals from China at a June conference.

“There are many components that rare earth minerals are in. And any of those that are coming from China require you to now go through export control,” she said. “And so there’s an additional layer of administrative process that has to happen.”

The process isn’t reliable, she added, noting that sometimes it goes “really smoothly,” while other times applications are not approved quickly. 

“Most frequently, it goes through; it just may take more time,” she said. 

For now, Ford is able to manage the cumbersome process, House said, but added that it has the potential to become a “larger issue for us.” 

Farley also told the outlet that he is optimistic about the developments in trade talks between the U.S. and China, and hopes that rare earth supply constraints will ease soon. He added that Ford is awaiting approval of applications with China’s Ministry of Commerce to export more rare earths. 

“We have applications into MOFCOM and they are being approved one at a time,” Farley told Bloomberg TV.