There is little doubt about the motive for Japan’s currency intervention. Koji Miyahara, the chairman of the Japan Shipowners’ Association, said there must be “zero tolerance” of a stronger currency because “it is impossible for Japan to win in global markets with the currency in the 80-yen range”. But the trouble with currencies is that there are two sides to any exchange rate. A weaker yen requires a stronger dollar or euro. A boon for Mr Miyahara’s members will be a bane for Greek shipowners.

While the action shows that Japan is addressing the most contentious subject in international economics – China’s intervention to hold down its own currency – it has chosen to do so alone.

Tim Murphy, a Republican US congressman who yesterday introduced legislation aimed at punishing China for manipulating its currency, said: “Japan must be thinking that if China can intervene, ‘why can’t we?’?” He added: “If this is a situation where every country is looking out for itself, that is a problem.”