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.

Trump regularly has said that he wants Canada to become a U.S. state, along with discussions about acquiring Greenland and the Panama Canal for security purposes. However, the mat