What are rare earth minerals, and why are they central to Trump’s threats against China?

The US trade war with China has a major sticking point: rare earth minerals.

China increased its restrictions on its rare earth exports Thursday, leading US President Donald Trump to threaten economic retaliation and imply he would cancel a meeting with Chinese President Xi Jinping during an upcoming visit to Asia.

The tussle over rare earths precedes the current administration; China for years has built up near-total control of the minerals as part of its wider industrial policy.

China first unveiled export controls on rare earth in April as a response to Trump’s “reciprocal tariffs” on Chinese goods announced then. After agreeing on a trade truce in Geneva, US officials had expected China to ease export restrictions on those minerals.

Here’s what you need to know about rare earths.