Trade wars, like real ones, are very much easier to start than to stop. The decision by Google to withhold its software from future Huawei smartphones, even if it will continue to support those presently on the market, comes after considerable pressure from the US government. Even so, it is a move that all parties will regret.

The pain for Huawei is obvious. Although it has been stockpiling chips and, presumably, preparing other defences, there is nothing it can sell to consumers outside China that does not depend on American software, and little that does not depend on American chips. As much as half of its global market could disappear, and that is without counting the 5G networking equipment which was the proximate cause of this quarrel. The ultimate cause, of course, is the American fear of losing its position of global pre-eminence, and the Chinese determination to realise that fear.