New Delhi, Feb. 20 -- US President Donald Trump seems to have expanded his tariffs further. He has announced another round of impositions targeting automobiles, semiconductor chips and pharmaceutical imports. "I probably will tell you that on April 2nd, but it will be in the neighbourhood of 25%," he reportedly said, referring to the rate he had in mind. These follow recent trade barriers against steel and aluminium imports, and also his declared plan for "reciprocal" levies.

With the contours of US trade policy shape-shifting by the day, it is getting harder to figure out how one proposal squares up with the next. The idea of reciprocity suggests that the US wants tariffs that mirror what its trade partners have. In many cases, that wou...