Three months later, Trump upbraided another American ally. On April 20, he signed an executive order calling for an investigation into whether foreign steel is a national-security threat to the United States. The executive order was aimed at China and Japan, but the president took the opportunity to lambast . . . Canada. “We can’t let Canada or anybody else take advantage and do what they did to our workers and to our farmers,” he said. Calling Canada’s trade conduct with the U.S. a “disgrace,” Trump added, “We’re going to have to get to the negotiating table with Canada very, very quickly.” Five days later, he fired the first shot in what might become a trade war with our neighbor to the north, putting a 20 percent tariff on Canadian lumber entering the United States. “People don’t realize Canada has been really rough with the United States,” he said. “We don’t want to be taken advantage of by other countries, and that’s stopping, and that’s stopping fast.”

Then there’s President Trump’s treatment of South Korea. During the same week he engaged in that contretemps with Canada, Trump threatened to pull out of the U.S.’s “horrible” trade deal with South Korea unless it was renegotiated to his satisfaction. Shares in the Hyundai Motor Company fell by 2.4 percent on the news of Trump’s comments. Far more significant, Trump told Reuters he wanted South Korea to pay for the $1 billion Terminal High Altitude Aerial Defense (THAAD) system the United States had already begun installing in Seongju. According to an earlier agreement, the cost of the system would be covered by the United States.