It feels as if liberal democracy is splitting at the seams. An authoritarian leader has abruptly closed America's borders to people from countries he doesn't like. He has, in many people's view, attacked the fundamental values of the country. The lives of thousands of blameless people have been thrown into chaos. Hundreds of thousands of protesters are marching in the streets. Americans voted for radical disruption, and they got it.

We Canadians are feeling profoundly lucky to be living in a multicultural country with liberal values. But for how long? A lot of us feel threatened, too. How can we assert those values and protect our interests when our giant neighbour looks as if it's descending into a dark place?

This is the tightrope the Trudeau government must walk. It won't be easy. Prime Minister Justin Trudeau and his cabinet ministers are fundamentally opposed to nearly everything that Trumpism stands for. Across the country, Canadians are urging them to stand up and resist, and not to submit to a despicable demagogue.

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So far, our government has done quite well. Mr. Trudeau has called on everyone he knows with ties in Washington. He has signalled his receptiveness to a NAFTA redo (not that we have a choice), even if he has to throw Mexico overboard. He has told his ministers to put a sock in it. This is wise. To Donald Trump, everything is personal, and Mr. Trump is perfectly capable of doing something nasty to us if we get up his nose.

But trade is one thing, and Mr. Trump's move to bar Muslims and refugees from specific countries is another. With that order, he trampled all over Mr. Trudeau's most deeply held beliefs. Mr. Trudeau couldn't help himself from taking a shot back. "To those fleeing persecution, terror & war, Canadians will welcome you, regardless of your faith," he tweeted Saturday. "Diversity is our strength."

The tweet captured media attention everywhere, including The New York Times and television network PBS. PBS interpreted it to mean that Mr. Trudeau was promising to take in refugees who'd been stranded by Mr. Trump. The news came along with a torrent of other misinformation. Initially, U.S. officials said that people who were already working legally in the United States would be banned, too. Canadian residents and dual citizens of named countries would also be banned. None of this turned out to be true, but the confusion was widespread.

Canadians, like much of the world, are outraged at Mr. Trump. And Mr. Trudeau is under tremendous pressure to do something – launch a global initiative to settle the stranded refugees, take in more refugees this year in Canada, grant visas to tech workers who've been barred from the U.S. (if there are any) or, at the very least, hold a parliamentary debate to denounce Mr. Trump's terrible decision.

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So what should we do? Probably nothing. What our government – and Canadians – need to keep in mind is that Canada is not the opposition party, and Mr. Trump's not our president. Whatever Mr. Trudeau may feel in his heart, his priority is to protect our interests, not signal our virtues.

I understand how he feels. But a wiser, more strategic leader would have kept those feelings to himself. It is not in Canada's national interest to attack the Trump administration, however awful it may be. America's immigration policy – no matter how hateful and irrational – is its business, not ours. The U.S. has its own robust laws and institutions, and these are already being used to challenge Mr. Trump's excesses. We should keep our noses out of it, except as it affects Canadian citizens and residents.

Their trade policies, by contrast, are very much our business, and call for vigorous engagement. We need to grasp the difference. We also need to grasp that lecturing a belligerent administration from our moral high horse will not help us achieve our other objectives – even if it makes our government more popular than ever.

As for the media, more thought and less heat might help. Mr. Trump's new immigration rules are not the Holocaust. Resettling the few thousand refugees rejected by Mr. Trump will do nothing to address the world's larger refugee problem, which is overwhelming.

Meantime, we should remind ourselves that opposition is not a strategy. The best way to preserve our values is to stay cool, collected and resolved. Emotional tweets are for the other guy, not us.