WITH A $752B TRADE RELATIONSHIP AT STAKE, TRUDEAU APPEARS TO BE WILLING TO ACT THE BETA DOG SUBORDINATE TO ALPHA DOG TRUMP. AND IF IT MEANS MEXICO SLIPS UNDER THE BILATERAL BUS, SO BE IT.

Justin Trudeau would probably have preferred to drink gasoline straight from the nozzle rather than mug for the cameras outside the White House with a president who, according to fresh reports in Vanity Fair, is in the process of “unravelling.”

Diplomacy demanded he fake a rictus smile Wednesday while Donald Trump complained about the press’s “disgusting” tendency to “write whatever they want to write.”

Patriotic duty compelled him to grin and bear it, as Trump performed his alpha dog routine during the photo op.

The London Daily Express asked a body language expert, Judi James, to interpret the exchange.

“Trudeau looks deliriously happy to go into body language suck-up mode with Trump here, nestling close beside him and grinning as Trump performs the pointing and thumbs-up rituals that he used to do with fans outside the lift at Trump Towers.

“Trump’s thumbs-up gestures imply a fun, easy-going relationship with Trudeau, although it also seems to signal a low level of respect. The comedy point is a subtle way to put down Trudeau’s visible status,” she said.

The Prime Minister’s patience in tolerating behaviour usually associated with an egocentric schoolyard bully was admirable, even if it fell short of the first commandment of Canadian foreign policy — to remain friendly with the United States while preserving self-respect.

But Trudeau has risked mortification in pursuit of a renewed NAFTA deal.

His “easy-going” relationship with Trump may end up being the difference between success and failure.

The latest edition of The Economist sets out what is at stake for the Liberal government. In an article that detailed the mistakes and mishaps afflicting Canada’s governing party, the paper argued that Trudeau’s popularity relies on a growing economy. “Most forecasters expect growth to slow in 2018 but to remain faster than in other G7 countries. Unless Mr. Trump starts a trade war,” it concluded.

But how do you strike a free trade deal with a protectionist?

Former prime minister Stephen Harper was also in Washington this week talking NAFTA. While he refrained from offering advice, he said what he had learned from trade negotiations with the European Union is that smaller players have to understand what a win would look like for the other side.

In the case of Canada-U.S. negotiations, it looks like Trump sees a win being a bilateral deal that jettisons Mexico.

That might be hard for him to engineer, unless Mexico walks away of its own volition.

Trade expert Larry Herman said the U.S. withdrawing from NAFTA would not be a simple matter and would require Congressional approval, which by many accounts would not be forthcoming.

But the situation would become considerably less complicated were the Mexicans to quit unilaterally — an eventuality the country’s foreign secretary mused about openly this week.

Canada’s prize is continued preferential access to the U.S., with whom we have a $752-billion-a-year trading relationship. By contrast, we trade just $27 billion in goods and services with Mexico every year.

Global Affairs minister Chrystia Freeland said earlier this year that Canada would not throw Mexico under the bus. Perhaps not. But were Tierra Azteca to slip beneath the wheels, Canada should not risk her own well-being.

Friends change but interests are enduring — and in many cases, those of Canada and the U.S. align more closely than those of Canada and Mexico.

On Thursday, General Motors announced it is ramping up production of its Chevrolet Equinox at two plants in Mexico, rather than at the GM CAMI plant at Ingersoll, Ont., where 3,000 autoworkers are on strike. This is language that Trump understands.

In Washington Thursday, the U.S. tabled its latest contentious demand — a sunset clause that would terminate a renewed NAFTA after five years. That comes on the heels of the introduction of far stricter Buy American procurement rules, and in advance of new rules for auto parts, which are expected to be announced as early as Friday.

Mexican senators have already laid out six so-called red lines which, if crossed, would lead them to reject a modified trade deal. They include the sunset clause, as well as U.S. content requirements for auto manufacturing and an end to the existing disputeresolution settlement.

It is easy to conclude the Americans are trying to goad the Mexicans into reacting, and at some stage, the Mexicans may oblige.

But Canada has to be more clear-eyed.

Trudeau’s acceptance of the beta dog subordinate role suggests he is prepared to do whatever is required to get a deal. “We have to be ready for anything,” he said.

That apparently includes playing second fiddle to a man who, if Vanity Fair is to be believed, is so unstable he is in danger of being removed from office by his own Cabinet.