US President Donald Trump's suggestion that Canada should become the 51st state of the United States has been met with defiance from some Canadians.

Adam Chapnick, a professor at the Canadian Forces College, a school for military officers, said that Trump's remarks have led to a heightened level of national unity.

"This began as a bit of a joke and then evolved into being more of a troll," Chapnick told China Daily. "While the president might genuinely think that Canada and Canadians would fare better as the 51st state, without a direct US military attack on Canada, there is no likelihood whatsoever of this happening.

A poll in January by the Angus Reid Institute found that 90 percent of Canadians oppose joining the US, and 4 out of 5 Americans say it should be up to Canada.

The poll also found that Americans are twice as likely to oppose (49 percent) Canada joining their nation than supportive (25 percent).

White House press secretary Karoline Leavitt said on Wednesday that Trump "feels strongly that it would be very beneficial for the Canadian people to be the 51st state of the United States. They wouldn't be paying for these tariffs. They'd have much lower taxes if they were part of our country."

On Thursday, however, Trump said he would again pause tariffs until April 2 on imports from Canada and Mexico covered by the US-Mexico-Canada trade agreement, offering the countries yet another reprieve. Ottawa responded in kind by delaying its own reciprocal tariffs on the US.

Trump, who recently has referred to Prime Minister Justin Trudeau as "governor", spoke via phone with him on Wednesday over the 25 percent tariffs imposed by the Trump administration this week.

The talk lasted 50 minutes; it was a "colorful call" and also "very substantive", Reuters reported.

Canadian Foreign Minister Mélanie Joly has told the BBC that she takes Trump's remarks on making Canada the 51st state "very seriously".

"This is not a joke anymore," Joly told Newsnight. "We're insulted. We're mad. We're angry."

Trudeau accused the US president of planning "a total collapse of the Canadian economy because that will make it easier to annex us".

"That is never going to happen. We will never be the 51st state," he told reporters on Tuesday. "This is a time to hit back hard and to demonstrate that a fight with Canada will have no winners."

Chapnick said that Trudeau's response has been measured and effective.

"I think that most Canadians have been quite pleased with PM Trudeau's response," he said. "He has been clear and firm without escalating, letting Americans know that Canada's goal is to restore the prosperous relationship we have long had, but also explaining that we will not be cowered by bullying."

While some younger Canadians have expressed openness to closer ties with the US for economic reasons, Chapnick said he believes it does not represent a shift in public sentiment.

"A small subset of young Canadians said that if the United States offered them a large amount of money in US dollars, they would be amenable to becoming Americans," Chapnick said. "The overwhelming majority of Canadians rejected this idea and continue to do so."

On how Canada should navigate its relationship with the US, Chapnick said: "Generally speaking, the way that we have. Speaking with a single voice (we have not been perfect on this), making clear that we do not want a trade war but that we will not be bullied."

Trump's comments on Canada are part of a broader pattern, Chapnick said, mentioning the president's musings about acquiring Greenland and retaking control of the Panama Canal.

"For now, cooperation on security and defense continues. I hope that we are able to keep things that way," he said.

Darrell Dorsk, owner of a glassworks store, said he believes Trump's 51st state remarks, while provocative, reflect certain economic realities that Canadians should not ignore.

"I don't think he's serious, but it's a provocative statement. The polls are saying that all the older Canadians are very much against this," Dorsk said.

"But the younger people, many of them say, ‘I wouldn't mind if I was living in America. I wouldn't mind if I had US dollars instead of the depreciating Canadian dollar,'" he said.

Dorsk said he doesn't believe that the tariffs, if put into effect, will be in place for long.

"However, he (Trump) has a point," Dorsk said. "Because of the trade imbalance, Canada derives a lot of benefit from being so close to the US."

Dorsk, who grew up in the US but has lived in Canada for 50 years, said he tries to see the issue from both sides: "I think Trump is a businessman, he's a capitalist, not a socialist. He wants fair trade and the balance of trade."

Ray, owner of a phone solutions business who did not give his last name, said that talk of Canada becoming a US state is "ridiculous".

"As a world leader, giving this kind of statement about a neighboring country that has been so good for centuries — this is derogatory, really unacceptable," he said.