The rise of the Chinese tech sector has helped power Beijing's rivalry with the United States . The recent efforts of the White House to counter China's tech champions, including its most profitable foreign venture, Huawei Technologies , have already taken effect, leading to a move by Google parent Alphabet Inc. to halt some business with the telecommunications giant. One possible response for China would be to restrict or ban exports of the rare earth elements critical to high-tech products. China's preeminence in the rare earths supply chain would make that a potent option; China has about a third of the world's reserves of the elements but controls a much larger portion of mining and refining operations. Rare earths are crucial for components across a variety of technologies.