Canadian Foreign Minister Melanie Joly sternly rebuked US President Donald Trump on Wednesday for his repeated assertions that Canada must become America’s “51st state.” Joly underscored that Canadians are highly offended by Trump’s statements and consider them to be a serious insult to their national sovereignty.

“This is not a joke anymore,” Joly told the BBC. “There’s a reason Canadians boo the American national anthem at hockey games we’re insulted, we’re mad, and we’re angry.”

Trump has often intimated that Canada should be under US control, even going so far as to suggest that Prime Minister Justin Trudeau might be a governor instead of a head of government. In a recent interview on Fox News, he reaffirmed his position, stating Canada would be better off as a US state while referencing a purported $200 billion trade deficit.

I believe Canada would be far better off as the 51st state because we’re losing $200 billion a year with Canada, and I’m not going to let that happen,” Trump said.

Joly’s words came as the two countries’ tensions rose, after the US administration placed 25% tariffs on Canadian products that became effective on March 4. Trudeau termed the tariffs “very dumb,” and accused Trump of favoring America’s relationship with Russia above the country’s best friend.

Canada retaliated by imposing retaliatory tariffs on more than $100 billion of American products. Trudeau, who was clearly irked, berated Washington’s move.

The US has initiated a trade war against its best friend and ally while appeasing Vladimir Putin, a murderous, lying dictator at the same time. Make that make sense,” he declared in a blunt news conference.

Trump, unfazed, fired back on social media, ridiculing Trudeau as “Governor of Canada” and threatening that any retaliatory tariffs would be met with immediate counter-measures.

Joly reaffirmed the position of Canada, saying, “We didn’t want this trade war. We followed all necessary security measures. The US must take responsibility for escalating tensions.”