In deference to this mutually beneficial relationship, Mexican President Enrique Peña Nieto has strained against provocation to get along with Mr. Trump. He invited him to a meeting in Mexico City last year, to Mr. Trump's political benefit and at Mr. Peña Nieto's own political risk. He was planning a visit to Washington next week to look for constructive cooperation.
Then, boom. Mr. Trump planted a stick of dynamite under a structure that leaders of various parties in both nations have been carefully constructing for decades. And for what?
The president first announced this week that he intended to proceed with construction of an expensive and unnecessary border wall, fulfilling a campaign promise based on misunderstandings of both the extent of illegal immigration and the best way to deal with it. Then Mr. Trump revived his pledge that Mexico would finance its construction. The humiliation was too much to bear for Mr. Peña Nieto, who faced understandable political pressure at home. The Mexican president canceled a scheduled meeting with Mr. Trump.
At that point, wiser heads still could have defused and de-escalated. Instead, White House press secretary Sean Spicer announced that the president is considering a new tax on Mexican imports to pay for his gratuitous wall. Mr. Spicer, without providing many details, suggested the tax would raise some $10 billion a year. He later explained that this is just one of several options. Depending on its design, such an imposition could indeed hurt Mexico. But it also would likely act as a tax on American consumers of Mexican goods. American consumers, that is, would pay for the wall by paying higher prices for Mexican-grown tomatoes, Mexican-sewn clothing and Mexican-built cars.
U.S. officials should reach out and seek to repair the week’s damage. It took the United States nearly a decade to recover from the economic wreckage of the last recession. A wealth-destroying trade war with one of America’s closest partners would threaten that long-sought recovery.