While other prime ministers grappled with American presidents who were unpopular among Canadians, the current situation has few direct parallels. Especially jarring to Canada is the new administration’s promise to revamp key components of Canada’s economy, like the North American Free Trade Agreement; threats to tighten the border; and demand for drastic increases in military spending by allies.

“We’re not very well organized for a knife fight in Canada,” said John Higginbotham, a senior fellow at Carleton University in Ottawa who served as the second-highest-ranking Canadian diplomat in Washington for six years. “It’s the most worrying thing seen in Canada-U.S. relations during my 35-year career.”