After their Oval Office encounter under the glare of the TV lights, Prime Minister Mark Carney and his U.S. counterpart retreated to the Roosevelt Room for a working lunch on Tuesday. Much of the mealtime chatter was about foreign policy issues,

Prime Minister Mark Carney did what he came to do in Washington on Tuesday—he reminded his counterpart to the south that Canada is a sovereign nation. But Donald Trump’s musings about taking over Canada (or Greenland,