Not since the first world war, when America’s government nationalised the railroad system, has it made the kind of investment it announced on July 10th. For $400m, the Department of Defence acquired a 15% stake in MP Materials, making it the largest shareholder in the country’s sole producer of rare-earth metals. The money will allow the business, with operations including a mine in California and a factory in Texas, to dramatically increase production of the magnets needed for fighter jets, electric vehicles, smartphones and more. On July 15th Apple, the iPhone-maker, joined in with a $500m deal to buy magnets from the company and help build a rare-earth recycling facility.