China has leverage it can use by limiting access to its rare earth supplies, but it does not want to sacrifice its reputation as a reliable supplier.

A new round of trade negotiations between the United States and China has started in London, with both sides trying to preserve a fragile truce brokered last month.

China returns to trade talks with the U.S. holding, from its view, a strong hand: Its economy is bearing up better than expected. And it has an ace card: rare earths.