Transportation Secretary Pete Buttigieg said the US must take steps to cut into China’s advantage in batteries used to power electric vehicles, saying building the refining capacity for key materials is “addressable.”

The US needs to build relationships domestically and internationally for raw materials and refining capacity, Buttigieg said in an interview with Bloomberg TV on Sunday. He is in Ise-Shima, Japan for a meeting Group of Seven counterparts.

“Refining capacity on many of the key materials for EV battery components is very concentrated in China,” he said. The US has to ensure it is “positioning to have an economically sensible, environmentally sensible and geopolitically stable approach to how we’re going to get these vitally important elements in our economy that are only to grow in importance.”

Chinese firms account for more than half of the EV battery market and satisfy as much as 90% of demand for some battery materials, according to BloombergNEF. Those economies of scale have made it almost impossible for US and European automakers to match the efficiency of their Chinese rivals.

See: China’s Gotion Has a New Battery Breakthrough: Hyperdrive

Ford Motor Co. and Contemporary Amperex Technology Co. Ltd., the world’s biggest maker of batteries for electric vehicles, plan to build a battery plant in Michigan. Bloomberg News reported in February that China will scrutinize the agreement to ensure the Chinese company’s core technology isn’t handed over to the US carmaker.

Also: China to Scrutinize Ford-CATL Deal to Ensure Top Tech Not Shared

While Beijing is pleased the deal showcases China’s prowess in the EV battery space, officials are concerned that competitive aspects of CATL’s technology could be given to or accessed by the American automaker, people familiar with the matter said, asking not to be named discussing Chinese government deliberations.