If you borrow $100, the old saw has it, you have a problem. Borrow $100m and your bank has a problem. So what happens when you borrow $900bn? In this case, China has the problem: it is stuck with these vast sums in US Treasury bonds, which it cannot possibly sell without spooking the market.

At the weekend, Beijing took what could be a baby step towards ensuring its problem does not get worse: it said it would “enhance exchange rate flexibility”. This was taken to mean China will reintroduce the “crawling peg”, which saw its currency appreciate 17 per cent against the dollar over three years until it was halted in 2008 to help Chinese exporters. Non-deliverable futures yesterday forecast a 2.3 per cent rise in the next year.

In principle, a stronger renminbi should mean lower exports, higher imports, a smaller current account surplus and so less need to recycle excess funds into foreign, primarily US, government bonds to avoid inflation. In practice, history suggests the opposite. In the three years before China's July 2005 revaluation, the country was adding an average of $13.5bn to its foreign reserves each month. In the three years after, it added $30.9bn a month.