The People’s Bank of China , the central bank, has just ordered commercial banks to halt cash transfers. ---Clip--- In short, there will be a three-day suspension of domestic renminbi transfers. There will also be a suspension, spanning nine calendar days, of conversions of renminbi to foreign currency. The specific reason given—“system maintenance” at the central bank—is preposterous. It is not credible that during the highest usage period in the year—the weeklong Lunar New Year holiday beginning January 31—the central bank would schedule an upgrade and shut down cash transfers. A better explanation is that the country’s banking system is...