In politics as in life, relationships matter. For Canada, the most important of those political relationships has long been between presidents and prime ministers and the teams of public servants working under them. Managed properly, these relationships can result in historic achievements but, when embittered, bilateral cooperation begins to grind against the political friction. In 1940, Mackenzie King and Franklin Roosevelt built the foundation of a continental alliance in an informal conversation while sitting in the president's private rail car outside Ogdensburg, New York. In 1986, Brian Mulroney sealed the most important trade deal in Canadian history, breaking through an impasse with Ronald Reagan's chief negotiator, James Baker, by threatening to phone his boss (Mulroney 2007). Conversely, in 2019, Justin Trudeau was caught mocking Donald Trump at a NATO summit in London, England, while the president, in turn, attacked the prime minister after the Canadian Broadcasting Corporation cut Trump's cameo from its airing of the movie Home Alone 2, tweeting: "I guess Justin T[rudeau] doesn't much like my making him pay up on NATO or Trade! [sic]" (Trump 2019b). 1 There is little doubt that Donald Trump's arrival in the White House in 2016 had a disruptive impact on traditional diplomatic norms. There is also a general agreement amongst scholars in the field, and those entrusted with maintaining and nurturing diplomatic relations, that the process of managing Canadian-American relations will now require a new set of guidelines and processes to handle a new degree of uncertainty. What most political leaders covet in working with both allies and adversaries is certainty and predictability. Canadian officials no longer enjoy this luxury. If anything, what Donald Trump has demonstrated since coming to office is that he is, and will remain, predictably unpredictable. This shift to unpredictability and occasionally bellicosity has jarred the Canadian political establishment and population more generally. It is all the more shocking given the overwhelming popularity that Trump's predecessor enjoyed north of the border. As John Kennedy, Cameron Anderson, and Laura B. Stephenson point out in this issue, Barack Obama enjoyed the confidence of 83 percent of Canadians. After Trump's surprise victory, 70 percent of Canadians expressed dissatisfaction with the former reality television star and political neophyte. Under Trump, more Canadians now see the US as a "negative force" in the world, more so even than North Korea. The shift is just as jarring at the top, with Prime Minister Trudeau forced to abandon his "bromance" (Boudreau 2019