As usual, there's a source which shows that trump just makes things up. This time about tariffs on the trade with Canada.
"You don't slap 25% tariffs on Canada's entire autos/auto parts imports to U.S. worth $61B in response to Canada's dairy tariffs (legal under WTO) affecting $0.2B of U.S. exports. It's disproportionate."
http://twitter.com/TradeNewsCentre