Since 2007, China has restricted exports of REEs (rare-earth elements) and imposed export tariffs, both to conserve resources and to give preference to Chinese manufacturers. In 2009, China supplied more than 96% of the world's REEs. Some outside China are concerned that because rare-earths are essential to some high-tech, renewable-energy, and defense-related technologies, the world should not be so reliant on a single supplier country
On September 22, 2010, China quietly enacted a ban on exports of rare-earths to Japan, a move suspected to be in retaliation for the Japanese arrest of a Chinese trawler captain in a territorial dispute. Because Japan and China are the only current sources for rare-earth magnetic material used in the US, a permanent disruption of Chinese rare-earth supply to Japan would leave China as the sole source. Jeff Green, a rare-earth lobbyist, said, "We are going to be 100 percent reliant on the Chinese to make the components for the defense supply chain." The House Committee on Science and Technology scheduled on September 23, 2010, the review of a detailed bill to subsidize the revival of the American rare-earths industry, including the reopening of the Mountain Pass mine.
After China doubled import duties on rare-earth concentrates to 25% as a result of the US-China trade war, MP Materials said, in May 2019, it will start its own partial processing operation in the United States, though full processing operations without Shenghe Resources have been delayed.   According to Bloomberg, China in 2019 established a plan for restricting  U.S. access to Chinese heavy rare earth elements, should the punitive step be deemed necessary. In 2022, the company announced that it had secured Department of Defense grants to support both light rare-earth elements (LREEs) and heavy rare earth elements (HREEs). The facility plans to begin separating NdPr oxide in early 2023.