Now that Donald Trump has won the US presidential election, some hard thinking is required on this side of the border.

Two of Trump’s main promises in particular have troubling implications for us. He has said he will impose a tariff of at least 10 percent on imports from Canada.

And he has promised to deport illegal immigrants back to their countries of origin. There are believed to be as many as 11 million such migrants, most Mexican by birth.

There are, of course, several points of uncertainty in these promises.

First, can he really deliver on them?

Republicans only have a three-seat majority in the Senate, and perhaps a four- or five-seat majority in the House of Representatives.

Nor can Trump count on automatic support in any of the bodies. Several Republicans in the Senate are known for their opposition to Trump’s ideas, and the House of Representatives is a famous place of contention.

But assuming he gets the support he needs, other questions arise.

As for tariffs, it’s unclear whether all Canadian exports would be affected, or just some.

The United States is by far Canada’s largest trading partner. Our annual exports to the United States exceed $600 billion, 10 times our exports to our next largest partner, the European Union.

A 10 percent tariff across the board could cost our economy $60 billion or more, a devastating setback.

Of the US exports, oil-based products account for approximately 180 billion dollars. Many Canadian experts believe Trump would rule these out, as driving up fuel costs would anger his supporters.

But even if oil products are effectively excluded, a 10 percent tariff on the rest could cost in the order of $40 billion. The question then becomes, how does Canada react?

Because just as the United States is our largest trading partner, Canada is America’s largest trading partner. US exports to Canada amount to approximately 500 billion dollars per year.

Obviously then a trade war would cost both countries dearly. Hopefully, the truth of this will form the basis of a negotiated outcome.

Trump’s other promise that has implications for Canada is his insistence on deporting illegal immigrants. What he actually means by this is unclear.

Does he intend to limit deportations to immigrants who have committed crimes in the United States, some of whom are known gang members, or does he intend to deport all illegal immigrants?

If the latter, it must be expected that possibly large numbers will try to take refuge in Canada. Are we ready to deal with this?

The federal government has already reduced the number of legal immigrants we admit each year, in an effort to reduce pressure on the housing market.

How would we respond to potentially thousands of refugees crossing our border? How would we deal with the impact on our health and social care systems?

It may be that any of these policies would create enough public backlash south of the border that Trump will have to back down. But it must be expected that in the first flush of the first victory he will at least start on them.

And it could have a significant impact on our federal election, which is coming up next year.

If, in the run-up to the election, there are signs of economic distress caused by tariffs, or social dislocation due to an influx of displaced immigrants, there will be pressure on each of the federal parties to formulate a response.

How effectively they deal with Trump’s threat may well determine who forms our next federal government.

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