Last weekend’s meeting of the G7, the leaders of the USA, China and five other powerful countries in Biarritz, had a familiar agenda: the full list of impending economy-wreckers, including the US-China trade war, Brexit, the conflict with Iran and paralysis on climate action.

In Hamlet, Claudius laments that “when sorrows come, they come not single spies but in battalion” and the list of threats is enough to sustain fears of a major international slowdown. But the threats are manifestations of a single underlying cause, namely the withdrawal of the United States from its traditional role in international affairs and especially in the international economy.