OTTAWA — When President Trump peeks out the window of Air Force One as it lands in Quebec on Friday before a meeting of Group of Seven leaders, he’s likely to spot a key “national security threat” at the heart of his recent trade action against Canada.

As the military version of the Boeing 747 circles over the Bagotville air base, it will fly over the vast aluminum smelters, hydroelectric transmission lines, port facilities and bright red bauxite ponds belonging to global mining firm Rio Tinto.

Powered by cheap hydro power from the Quebec region’s vast water resources, these facilities have been the center of Canada’s aluminum industry since before the Second World War and still produce a big portion of Canada’s output of the metal, most of which is exported to the United States.

In imposing a 10 percent tariff on aluminum imports from Canada, as well as a 25 percent levy on imports of steel, Trump cited the need to protect U.S. “national security” from the dangers of excessive dependence on suppliers like Canada, Mexico and the European Union. The administration argues that the increased imports have led to the closing of U.S. steel and aluminum plants, leaving the U.S. industry at risk of becoming unsustainable, thus threatening national security.

Canadian officials, led by Prime Minister Justin Trudeau, say that calling Canada a national security threat is “insulting” and “absurd,” pointing to the irony of Trump’s use of the Bagotville base as a sign he misunderstands Canada’s history as an American ally and supplier of strategic metals.

Trump’s trip will be his first to Canada as president, a break in the tradition that used to see American presidents make their first foreign visit north of the border.

The origins of the Bagotville base go back to the early 1940s, when U.S. aluminum interests hacked through Quebec’s thick conifer forests to build dams to expand the massive Alcan aluminum smelting complex that was to provide the lightweight metal essential to the war effort.

“The main reason for the base was to protect the aluminum plants as well as the infrastructure, the dams and the dikes that produced the power to make the aluminum,” said Marc-Andre Valiquette, an amateur historian, former Canadian forces pilot and author of a recent history of the base.

“It was built in 1940 and 1941. Europe was losing the war. Britain was threatened. U-boats were coming down the St. Lawrence River,” he said. The aluminum produced by Alcan was essential for the construction of war planes in the United States, Canada and Britain, so the Royal Canadian Air Force built the base to protect those facilities.

Alcan publicity from the period makes a clear link to the war effort. “Water power, one of Canada’s greatest natural resources, has gone to war,” said one magazine ad picturing a roaring river. “In the Saguenay Valley, it is generating energy in tremendous volume to transform British Guiana bauxite into shiny light aluminum, the metal of air mastery and victory.”

Although the aluminum complex now belongs to British-based Rio Tinto, the region’s American heritage is still evident. Arvida, the planned community built to house Alcan workers, was named for Arthur Vining Davis, the founder of Aluminum Co. of America (Alcoa). One of the big thoroughfares in the area is Mellon Boulevard, named after Andrew Mellon, the Pittsburgh banker, Alcoa investor and U.S. treasury secretary.

And as Trudeau repeats whenever interviewed on American television, Canadian aluminum still ends up in U.S. fighter aircraft and its steel is used in American tanks.

James Hasik, senior fellow at the Brent Scowcroft Center on International Security at the Atlantic Council, said that nobody he knows in the national security community believes that invocation of the Section 232 national security clause has any substance.

“I can’t imagine the circumstances in which a Canadian federal government would try to choke off aluminum supplies to the U.S.,” Hasik said.

The Bagotville base is about 70 miles north of La Malbaie, the resort town on the St. Lawrence River where the summit will take place. Trump, along with other world leaders, is expected to take helicopters to the summit site at the Manoir Richelieu Hotel.

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