China has been buying up lots of rare earth materials that go into batteries.
China isn’t buying up rare earths in markets in a speculative play to drive up prices. However, they do have 97% of the world’s reserves of rare earths at current market prices, and have imposed limitations on exports.
China acts in China’s interest ... just like every other nation, but a little bit more intelligently. Their limitations on exports of rare earths is strategic in nature, not speculative.