No more than a narrow window of opportunity remains if we are to prevent an unnecessary global recession. As China and the US decouple, disruptive trade wars are intensifying and threaten to descend into currency wars; import, export, investment and technology bans; and financial fire sales that will destroy millions of jobs worldwide. It seems barely credible that the world is being brought to its knees by one economy, outside of which live 96% of the population, who produce 84% of the world’s manufactured goods. But even though US officials have previously talked of a tariff policy of “escalate to...