MONTREAL -- Chalk up another victim to the coronavirus that has swept across the globe: the decades-old amity that tied Canada to the United States in cross-border marriages and commercial relationships, that deepened during World War II, that took the form of three landmark 20th-century free-trade agreements, and that burst into full flower when Canada welcomed American jetliners and their passengers to Newfoundland after the 2001 terrorist attacks.
These new tensions -- flaring now that fear of COVID-19 has gone viral -- have swept away the welcome mat that Americans for generations have crossed to enter Canada for vacations, family visits and business. They are a fresh example of the diminishment of American influence in the first quarter of the 21st century.
On the North American continent, the result is an unexpected and perhaps unprecedented case of social distancing.
True to the maxim of Canada's Inuit, that all threats come from the south, Andre Picard, a columnist in The Globe and Mail newspaper, riffed off the old adage that when the United States sneezes, Canada catches a cold. "What happens when the U.S. coughs? When it coughs that dry hacking coronavirus cough?" he asked. "We're about to find out."
This spring, with neighboring New York and Washington considered hotbeds of the menacing virus and with Americans stocking up on firearms, the United States is at risk of losing its cultural and emotional most-favored-nation status here.
"There's no precedent for this," said Stephane Paquin, a specialist in Canadian international relations at the Montreal campus of the National School of Public Administration (ENAP). "And of course there is the Trump factor that doesn't make things better."
President Donald J. Trump's swiftly changing views of the seriousness of the virus and the nation's response to the COVID-19 threat have exacerbated concerns in Canada.
"Americans have been behind the curve and haven't done a lot of testing," said Christopher Kirkey, director of the Center for the Study of Canada at the State University of New York College at Plattsburgh. "So it is natural that people think Americans pose a threat. There is a lot of fear about this."
Then came the military threat: Trump's trial balloon about posting American soldiers at the Canadian border.
The response from Ottawa was swift and angry. "We don't think this is the right way to treat a trusted friend and military ally," said Deputy Prime Minister Chrystia Freeland.
To be sure, there have been squalls in the two countries' relationships before. Former Prime Minister Stephen Harper once noted that an American invasion of Canada during the War of 1812 "made Canada possible." Canadians looked askance as American involvement in Vietnam deepened and were horrified when President Lyndon B. Johnson, meeting with Prime Minister Lester B. Pearson at Camp David in 1965, grabbed the Nobel Peace Prize winner and shook him while remonstrating that the Canadians' critique of American war policies was unwelcome.
When, two years ago, Trump invoked "national security" to defend his decision to impose steel and aluminum tariffs on Canada, Freeland, then Canada's foreign minister, mocked the notion her country was a threat to the more powerful nation south of the border.
"I would just say to all of Canada's American friends ... Seriously?"
Though deep ties of anti-Americanism swirl along with deep personal ties, the two countries have longstanding links.
Franklin Delano Roosevelt, who vacationed (and likely contracted polio) at Campobello, New Brunswick, traveled to Windsor, Ontario, in 1937. There he assured Prime Minister William Lyon Mackenzie King that the U.S., which had mounted repeated invasions of its neighbor, would defend Canada from foreign incursions.
These ties have physical form in the bridges that connect the two countries, particularly the poignantly named Peace Bridge that connects Buffalo with Fort Erie, Ontario, and in the canals, locks and dredged waterways of the 2,300-mile St. Lawrence Seaway that extends from the Atlantic Ocean to Lake Superior and was dedicated jointly by Queen Elizabeth II and President Dwight D. Eisenhower in 1959.
John F. Kennedy, who considered his counterpart, Prime Minister John Diefenbaker, an "S.O.B.," nonetheless is remembered especially fondly in Montreal -- where a downtown street is called "Avenue du President-Kennedy" -- for delivering, in a 1961 speech in Ottawa, a line that Canadians revere: "Geography has made us neighbors. History has made us friends." George W. Bush took it one step further, calling the two countries "family."
"These two countries have always been close," said former Gov. Michael S. Dukakis of Massachusetts, a state that in 2018 exported $3 billion in goods to Canada, more than a tenth of its total exports. "They've got a pretty impressive prime minister. How are we looking these days?"
Canada -- which University of Toronto historian Robert Bothwell once described as oscillating "on the American horizon somewhere between an anomaly and a conundrum" -- was bewildered when Trump attempted to cut off supplies of the N95 masks, an impulse from which the White House finally backed away.
Doug Ford, Ontario's premier whose rise inspired comparisons to Trump, said the episode was "like one of your family members (says), 'OK, you go starve and we'll go feast on the rest of the meal.'" Claude Elliott, mayor of the Newfoundland city of Gander -- where American airliner passengers found comfort and comfort-food meals when forced to land after the 9/11 attacks -- channeled the cooperation celebrated in the Broadway show "Come From Away," saying: "When we come to those times of tragedy in our life, we need everybody helping each other."
Michael Hawes, the director of Fulbright Canada, acknowledged that, as he put it, "This is a difficult moment in all relations" and suggested that "this may not be any worse than others."
But this is not a relationship like any other -- an undefended border a continent wide, with 150,000 automobiles during normal times daily traversing 119 border crossings, and with three-quarters of Canada's exports headed to the United States. And it is a time in the relationship like few others.
"It is a special moment in Canada, because the shift in the relationship's tone has been so dramatic and so unwelcome, violating the special nature of the ties," said D. Munroe Eagles, a Nova Scotian who teaches at the University at Buffalo. "Things are worse now than they have been in a long time."
(David M. Shribman is the former executive editor of the Pittsburgh Post-Gazette. Follow him on Twitter at ShribmanPG.)