Michael Hiltzik of the L.A. Times writes that a new study has found that Trump-enacted tariffs have been costly for U.S. consumers — and especially hard on producers in America's agricultural heartland, where many of his most ardent supporters reside. According to trade experts, he says, Trump's trade war with China is "based on fundamental misunderstandings of how international trade works, little consistency in applying tariffs to products or sectors, and little consideration of how the trade war would affect the economy."