Late last year in Beijing, officials from several of China’s technology, trade and defence agencies were called to a series of secret meetings with a single purpose: to respond to America’s crippling restrictions on selling computer chips to Chinese companies.

In July, Beijing announced its response: it imposed restrictions on the exports of gallium and germanium, metals used in the production of a number of strategically important products, including electric vehicles, microchips and some military weapons systems.

“We had many options,” says one official directly involved in the talks. “This was not our most extreme move . . . it was a deterrent.”