Open this photo in gallery In normal times, with a normal president, the extremely rookie move by Justin Trudeau, seen here on Dec. 3, 2019, of getting caught on camera badmouthing a fellow leader would begin and end with the Prime Minister’s embarrassment. Yui Mok/The Associated Press

We might never know the name of the brave person who, I think it is fair to assume, must have talked U.S. President Donald Trump out of ordering U.S. Army Reserve troops to storm the Canadian border Tuesday evening. By that time, the President would have seen the clip of Prime Minister Justin Trudeau appearing to mock him in a conversation with French, British and Dutch leaders at the NATO Summit, and likely started querying those around him as to how to cut off resource supplies into Canada and reposition Alaskan interceptor missiles to point toward Whitehorse. A modern day War Plan Red.

But by the power of targeted persuasion, or by luck, or by someone switching the channel on the TV in the President’s suite, Canadians awoke Wednesday in a still-free country, where our border with the United States is plagued only by long wait times. Eventually, Canada will have to erect a statue in tribute to the unnamed aide.

I am only partially joking here, seeing as the U.S. President is someone who will, for example, move on enormously impactful foreign-policy decisions in the Middle East because of a pleasant phone call.

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In normal times, with a normal president, Mr. Trudeau’s extremely rookie move of getting caught on camera badmouthing a fellow leader would begin and end with the Prime Minister’s embarrassment.

Indeed, this behaviour is unfortunately part and parcel of what we have come to expect from Mr. Trudeau when he travels abroad. Something happens – maybe the cabin pressure in his plane is off – but Mr. Trudeau will reliably disembark with a bizarre affinity for local dress, sudden forgetfulness about his ethical obligations or a massive miscalculation of his diplomatic ties. It’s awkward and unpleasant, but we all survive. But we are not in normal times, and this is not a normal president.

Mr. Trump has repeatedly demonstrated that he will use institutional mechanisms as personal tools to reward friends and punish enemies. The most obvious example of this is currently occupying Congress, which is considering whether to impeach the President over allegations he withheld military aid to Ukraine in order to press the Zelensky administration to investigate political rival Joe Biden.

In other areas, the United States’ diplomatic relationship with foreign powers mirrors the President’s personal relationship with their leaders. Mr. Trump’s prior tough rhetoric about North Korean aggression and militarization has been quelled by his affinity for Kim Jong-un, whom the President has called “capable” and “very talented.” And the U.S. government’s response to the 2018 execution of U.S.-based Saudi journalist Jamal Khashoggi was essentially non-existent, with Mr. Trump lavishing praise on his “friend” Crown Prince Mohammed bin Salman ever since.

Traditional alliances seem to mean little to the Trump administration, as former defence secretary James Mattis noted in his resignation letter last year. The most profound demonstration of that was Mr. Trump’s order to remove all U.S. troops from northern Syria back in October, abandoning Kurdish allies in the region and instantly betraying the principles of American loyalty.

Canada has felt this betrayal, too – albeit without the life and death consequences. When the U.S. slapped tariffs on Canadian steel in 2018, it did so with the spurious justification that Canada posed a national-security threat. Mr. Trump then called Canada’s retaliatory tariffs “illegal,” which all happened around the same time White House trade adviser Peter Navarro attacked Mr. Trudeau on Fox News, saying, “There’s a special place in hell for any foreign leader that engages in bad-faith diplomacy with President Donald J. Trump.”

Since then, the U.S. has resolved many of its differences with us (and dropped its steel and aluminum tariffs), but the President, of course, remains as volatile as ever. And while he might not assemble troops along the Detroit-Windsor border because Mr. Trudeau poked fun at him at NATO, the President is certainly petty enough to be a little more reticent to help Canada retrieve two detained citizens in China, or perhaps opt to delay finalizing USMCA ratification.

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Most world leaders have recognized by now that they need to be the adults in the room when it comes to Mr. Trump. Mr. Trudeau was caught on video acting like a teenage boy, and unfortunately Canada might have to bear the consequences.

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