Brussels is playing host to foreign ministers from 32 countries this week to mark 75 years since the formation of the North Atlantic Treaty Organization. 

As the alliance celebrates its anniversary, it's staring down the familiar threat of an unpredictable Russia. 

It's also bracing for the prospect of another perilous situation that it has faced once before: a Donald Trump presidency. 

The front-runner in the race to become the Republican nominee recently said he warned allies while he was president that the U.S. would not protect "delinquent" countries that aren't meeting spending targets.

"'No, I would not protect you. In fact, I would encourage (Russia) to do whatever the hell they want. You gotta pay. You gotta pay your bills,'" Trump recounted saying.

Despite similar comments during his presidency, Trump did endorse NATO's collective defence article. But there are worries things will be different if he returns to the White House after November's vote.

Brett Bruen, the former director of global engagement in the administration of former Democratic president Barack Obama, said there may be fewer "emergency brakes" in place, with many longtime Republicans shying away from being involved in a Trump White House 2.0.

And in that case, allies will need a plan to win him over. Think big, splashy defence spending announcements, with Trump as guest of honour at a military parade, Bruen said.

The key, he said, is "to package it up and put a really big, bright bow on top that makes it look like he single-handedly, brilliantly reformed NATO."

"Trump is, at the end of the day, a negotiator and a businessman who I think could be co-opted, convinced into staying in NATO," said Bruen. 

At the same time, Republicans and Democrats alike are questioning whether allies are getting more than they're giving.

There is a fierce debate in Washington around continued support for aspiring NATO member Ukraine in its war against Russia.

"The real question, I think, at this moment, is whether or not NATO is in its last gasp of strength," said Bruen. 

Kerry Buck, a former Canadian ambassador to NATO, said Russia's invasion has forced the alliance to become stronger. European countries "have started to get a lot more serious about defence," she said.

"If the U.S. starts to downgrade its presence, I don't see NATO crumbling right away."

On Wednesday, reporters in Brussels asked Foreign Affairs Minister Mélanie Joly if she's concerned a future Trump administration would mean an end to American help for Ukraine. 

"I'm convinced that the U.S. will find a way to continue to support Ukraine," she said.

Eighteen allies are set to meet or exceed the agreed-upon target of spending a minimum of two per cent of GDP on defence this year, including 20 per cent of that funding on major new equipment. 

That was hailed as positive news by NATO Secretary-General Jens Stoltenberg, but the data also show Canada is lagging behind, spending just 1.33 per cent of its GDP on defence. 

"This is a bad public look," said Anessa Kimball, a professor of political science and international relations at the University of Laval. 

While Canada is not alone, it has farther to go than any other ally. To bridge the gap, it would need to spend an estimated $18 billion more a year.

Defence Minister Bill Blair told a national defence and security conference last month that the country "must and will" spend more. At the same time, his department has been told to find $1 billion in savings in each of the next three years.

At the last leaders' summit in Lithuania last July, Prime Minister Justin Trudeau insisted allies were not pressuring him to come up with the money. 

But Kimball said it's becoming clear they want to see a plan for how Canada would get there. 

She said the anniversary is an opportunity, and Canada could advocate for NATO to modernize its spending agreement. 

For instance, Canada has a lot of work to do to build critical infrastructure — roads, airports, fuel and internet — in the North. That kind of spending would not count as defence and security for NATO purposes, but Kimball said there's an argument that it ought to. 

"Other countries are better at getting those things included into their defence spending because they have done this legislatively," she said, pointing to Belgium, which has designated railways as critical national security and defence infrastructure.

Bruen said Canada will need to come up with more money, Trump or no Trump. "I don't think Canada can do this on the cheap." 

To get political buy-in at home, Kimball said Canada can be a leader in the alliance's emerging priorities.

"NATO taking on climate change and becoming interested in the Arctic, for example, makes NATO more relevant for Canada's defence and security," she said.

All Arctic countries except Russia are now members, with Sweden and Finland joining in the last two years. 

Buck said that gives NATO a reason to take a strategic interest in a region it has steered clear of in the past, a region Canada is already focused on.

"We should use multilateral bodies like NATO to partner more with the other Arctic nations and ensure that we have better military readiness, better military presence, better civilian presence," she said.

"To make sure that our Arctic remains our Arctic."

This report by The Canadian Press was first published April 4, 2024. 

— With files from The Associated Press.