Canadian Prime Minister Mark Carney said emphatically Tuesday that Canada is "not for sale" and "won't be for sale, ever" in an Oval Office meeting with President Trump, moments after Mr. Trump called the border between the U.S. and Canada "artificial" and romanticized the idea of Canada joining the U.S.

U.S. President Donald Trump and new Canadian Prime Minister Mark Carney faced off in the Oval Office and showed no signs of retreating from their gaping differences in an ongoing trade war that has shattered decades of trust between the two countries.