Summary Box: China defends rare earths limits

DEFENSE: China defended curbs on production of rare earths used in mobile phones and other high-tech products, saying it needs to limit environmental damage and conserve scarce resources.

THE SPARK: The United States, Europe and Japan are filing trade complaints with the World Trade Organization.

THE SUPPLIES: Global manufacturers that depend on Chinese supplies were alarmed by Beijing’s 2009 decision to limit exports while it builds up an industry to produce lightweight magnets and other goods that use them. China has about 30 percent of rare earths deposits but accounts for 97 percent of production.