China should let its currency rise. Such has been the desperate, decade-long complaint from the US and its politicians. China’s manipulation of its currency is a popular scapegoat both for the financial crisis and for the extinction of US manufacturing.

An appreciation is plainly in China’s urgent interests. And the rest of the world, including the US, is beginning to grasp that it has reason to fear the consequences if it does. On Wednesday and Thursday of this week, China’s authorities at one point allowed the renminbi to appreciate against the dollar by a greater percentage than in any two-day period since its managed rise first started in 2005. These moves remain tiny; but they combine with official criticism of the US, a growing need to combat Chinese inflation and much Chinese commentary favouring a change of policy to suggest that the renminbi may soon be allowed to take flight. A widening of its trading bands might be a first incremental step.

Unlike the first managed appreciation, from 2005 to 2008, the current “appreciation” has done nothing to help domestic inflation. By tying to the dollar, a currency sinking like a stone, the renminbi has depreciated against all currencies on a trade-weighted basis, JPMorgan data show. A drastic shift is needed. That will mean exporting its inflation. It also means buying fewer treasuries, or even selling some, which would in turn counteract any efforts at “quantitative easing” – buying bonds to keep US yields low.