Last week Nigeria’s central bank announced something that might make American politicians blink. Kingsley Moghalu, the deputy governor, pledged to convert almost a 10th of Nigeria’s $43bn reserves from dollars to the Chinese currency. “Ultimately the renminbi is likely to become a global convertible currency,” he explained, noting that “the future of international economics and trade will shift in large part to business with and by China”.

Only 0.01 per cent of central bank foreign exchange reserves are held in renminbi, compared with 60 per cent in dollars and 25 per cent in euros. But Patrick Zweifel, chief economist at Pictet Asset Management, believes renminbi reserves could reach 30 per cent of the total by 2025, posing a challenge to the dollar’s pre-eminence.

He is not alone. Such forecasts have much to do with China’s rising economic might and the gradual liberalisation of its currency. But they reflect alarm and irritation about America, too. The US current account deficit, rising government debt, the hangover from a financial crisis and political gridlock have prompted economists and investors to warn of a looming dollar decline. Hence the keenness of Nigeria and others to reduce their exposure to the US currency, and escape from being tethered to swings in American policy.