The Globe and Mail reports in its Friday edition that since the Great Depression, the arc of trade history has bent toward lower tariffs and freer trade; not any more. The Globe's Tony Keller writes that under President Donald Trump, Washington is chaotically dismantling what it once built. If your mind is still in the old world, then the constant attacks on Canada -- the latest being the announcement of pending 50-per-cent tariffs on some Canadian goods -- is hard to understand. So are Thursday's sweeping tariffs on all major U.S. trading partners, including Canada, on the absurd pretext of combatting forced labour. But Mr. Trump doesn't share assumptions about the mutual benefits of trade. His goal is not a U.S.-Mexico-Canada Agreement that frees up more trade, but a USMCA that imposes new trade restrictions -- on us. Mr. Trump's brain is as disorganized as a library with a scrambled card catalogue, and ragging the puck on the penalty kill is always a sound strategy. Mr. Trump seems determined to demolish USMCA, but he will probably be a lame-duck President after the November midterms. Canada should keep calm and carry on while the crack house downstairs enjoys its bender. When they get out of rehab, we'll be here.