The renminbi, not for the first or last time, is the subject of a cacophonous debate in Washington and rising tensions between the US and China. When this happened in the spring, a series of confidence-building measures culminated in Beijing’s announcement in June that it would allow its currency to trade more flexibly. Sabre-rattling and subsequent de-escalation has become a pattern but with every occurrence the risks of new financial and economic turbulence are growing.

Recent US pressure on the issue, including last week’s referral by the administration of two complaints against China to the World Trade Organisation, can be explained partly by the unstable nature of US politics ahead of November’s Congressional elections. But this is about more than the need to curry favour among voters. Rather, the two giants of the world economy – one the biggest debtor, the other the biggest creditor – are skirmishing over how the global system should work in the aftermath of the financial crisis. At its heart, the debate is about who is to blame for economic imbalances and whose responsibility it is to right them.

For once, the answer is simple. The US and other western nations have been shocked into saving more and lowering private and public debts over the coming years. It follows that, if the world system is to function smoothly, someone has to save less. China and the other creditor nations are now in pole position to take the needed initiatives.