Donald Trump doesn’t want Canada’s aluminum, steel, lumber or cars. Could oil emerge next on this tariff-fuelled northern hate list? It might if he can find substitute supplies. How about Venezuela’s? Going after Venezuela’s alleged narco-traffickers alone does not justify the formidable U.S. military buildup off the country’s waters; going after its oil might.

The biggest U.S. armada assembled since the 1991 Gulf War is steaming off Venezuela’s coast. The array of weapons in the southern Caribbean and on nearby military bases includes the USS Gerald R. Ford, the world’s largest aircraft carrier, guided-missile destroyers, amphibious assault ships and – ominously – equipment, including Osprey tilt-rotor aircraft, that is used by elite special forces. Various reports say those forces might include soldiers trained in risky infiltration missions, seizing airfields among them.

Mr. Trump wants regime change – he has invited Venezuelan President Nicolás Maduro to disappear. He might also want war. Certainly, he is ramping up the war rhetoric.

Trump threatens Maduro as U.S. steps up Venezuela campaign

His blockade of U.S.-sanctioned oil tankers, which began on Dec. 17, will continue, he said, “until such time as they return to the United States all the oil, land and other assets they stole from us,” a reference to the staged nationalization of the Venezuelan oil industry since the 1970s under then presidents Carlos Andrés Pérez and Hugo Chávez. Mr. Trump declared the Maduro regime a foreign terrorist organization because of Mr. Maduro’s alleged support of narcoterrorists, and has not ruled out an armed conflict that could see U.S. boots on the ground.

The enormous military buildup says Mr. Trump is not joking. By now, it’s obvious that his pre-inauguration isolationist stance was a charade. Since he became President again almost a year ago, the U.S. has backed Israel’s war in Gaza against Hamas and in Lebanon against Hezbollah; bombed Iranian nuclear sites; attacked Houthi-controlled military assets in Yemen; attacked Islamic State militants in Nigeria; and continued military and financial support for Ukraine (though at lower levels than the Joe Biden administration did).

An invasion of Venezuela does not seem out of the question given the allure of the prize – access to the world’s biggest proven oil reserves. Between the U.S. shale oil gusher and exports from Canada, currently running at some 4.2 million barrels a day, Mr. Trump’s America is swimming in oil. But the shale reserves won’t last forever and there are already signs that output is peaking.

Opinion: At least one part of the U.S. campaign against Venezuela makes sense: taking on the ‘dark fleet’

Venezuela was one of the first petrostates and helped launch Royal Dutch Shell onto the global energy stage. The country became a production powerhouse in the late 1920s and used oil exports to create a one-product-wonder economy. From the 1950s through the 1970s, it was one of the world’s wealthiest countries, measured on a per capita basis.

Since then, it has squandered its geological blessing. Venezuelan governments failed to manage boom-and-bust cycles well, created an overly expensive welfare state and spent too little on energy infrastructure. The nationalizations sent engineering talent fleeing, and the industry never fully recovered from a two-month strike that began in late 2002.

Then sanctions hit, initially in retaliation for the Chavez oil-industry nationalizations. Venezuela’s production peaked at about 3.5 million b/d in the late 1990s. Today, it’s one million or less and could plunge if Mr. Trump’s armada-backed embargo does not prove porous.

But oil does not rot in the ground. The reserves are still there. Canada should be worried.

Under Prime Minister Mark Carney, having shed his clean-energy pleadings, the Liberal government is backing oil-and-gas developments, big time, including boosting exports to the U.S., possibly by reviving the Keystone XL pipeline that would run from the Alberta oil sands to Nebraska. The pipeline was never endorsed by Barack Obama and Mr. Biden when they were in the White House.

There is a credible scenario in which Canada’s market share of U.S. oil consumption falls. That would happen if Venezuela becomes an oil-export powerhouse again. The Orinoco heavy crude produced in Venezuela has the same general makeup as oil sands’ crude, meaning that some of the U.S. oil refineries, especially those along Texas and Louisiana Gulf of Mexico coasts, could switch from Alberta crude to Venezuela crude without breaking a sweat.

Mr. Trump could use military action, perhaps an invasion, to force regime change in Venezuela. A U.S.-backed transitional government could invite U.S. oil companies back into the Venezuelan oil industry to ramp up production to feed U.S. refineries. Fixing the Venezuelan oil industry could take years and cost tens of billions of dollars. Whatever the timeline, Canada would suffer. More Venezuelan crude sent to the U.S. would translate into less need for Canadian crude.

The scenario might seem far-fetched, but Mr. Trump is not beyond reckless and globally destabilizing ideas. He wants to make Canada the 51^st state and is intensifying his campaign to “buy” Greenland, allegedly for security reasons, though it cannot be lost on him that the country, an autonomous territory within the Kingdom of Denmark, is thought to be brimming with rare earth metals and other potentially valuable resources.

Mr. Trump’s use of a coup d’etat backed or forced by the U.S. military cannot be ruled out in Venezuela. Canada beware. The Keystone XL pipeline may never be needed. Mr. Trump has zero loyalty to Canada or its exports, including oil.