A Win at the Border

President Trump evidently knows something about the art of the tariff threat. His unorthodox Twitter diplomacy has gotten Mexico to make potentially important public commitments on immigration enforcement. Trump said he was going to slap steadily escalating tariffs on Mexico unless it did more to help with the border crisis, a threat with huge downside risks. If implemented, the tariffs would have been disruptive at a time when U.S. growth is perhaps slowing, been an economic gut-punch to an all