It is not the most enticing reading material: “Macroeconomic and Foreign Exchange Policies of Major Trading Partners of the United States.” But this 59-page report, issued last month by the US Treasury Department, reveals much about contemporary America. Remember the joint intervention by Japan and the United States in the international currency market to prop up the yen at the end of July? By now, everyone knows it didn’t work, a waste of monetary resources for both countries while earning a...