(FILES) US Presidnt Donald Trump greets Canadian Prime Minister Justin Trudeau at the White House in Washington, DC, on June 20, 2019. The political circumstances that surrounded the publication of "Ultimatum," once a best-selling novel that imagined an American effort to annex Canada, may ring familiar to anyone following recent headlines. "Ultimatum," published in 1973, is authored by D-Day veteran Richard Rohmer, the honorary lieutenant general of the Canadian Armed Forces, who recently turned 101. Still an avid news consumer and writer, Rohmer told AFP that remarks by President-elect Donald Trump implying that Canada could be absorbed by the United States should not be laughed off. (Photo by NICHOLAS KAMM / AFP) (Photo by NICHOLAS KAMM/AFP via Getty Images)