Charles and David Koch are two of the ten richest Americans. They’ve been major donors to conservative and libertarian causes, funding candidates for office, the Tea Party movement, and even university economics departments. They sat out Donald Trump’s campaign for President, characterizing his race against Hillary Clinton as the choice between cancer and a heart attack. Now Trump has promised a wave of tariffs on products from China, Mexico, Canada, and the European Union, which violates their principles and would hurt the business of Koch Industries.  Jane Mayer has reported on the Kochs and their political activities for years. She tells David Remnick that the brothers plan to spend thirty million dollars on advertising against the tariffs, right as the midterm elections offer voters a referendum on the Trump Presidency. But, as much as trade is a flash point in the Republican Party, Mayer thinks that, in the most critical areas of environmental deregulation and corporate taxes, the Kochs have every reason to be satisfied with the Administration.