Yesterday China said it would limit exports of gallium and germanium, essential albeit in tiny quantities for chipmaking, communications equipment, night vision goggles and satellite-mounted solar cells. In response, Washington is planning to prevent Chinese firms accessing AI computing capability via the cloud. Amazon Web Services and Microsoft’s Azure, for example, will have to get US government permission before selling cloud services to Chinese companies. If those companies work in security or for the military, permission would be denied on the same basis that the US has banned the export of AI-enabling chips to China since last October – namely that China is now an adversary, not a partner. This wasn’t how the cloud was meant to work. It was supposed to bring the world together. Nor is it the sort of prelude Janet Yellen, the US Treasury Secretary, would have wanted for her trip to Beijing later this week. Like Secretary of State Tony Blinken two weeks ago, Yellen will have to hope that keeping communications channels open counts as success, even if the two sides use them to talk past each other.