Trump and Canada Trade Tensions Escalate Following Failed Negotiations

US President Donald Trump has hit back at Canada after Prime Minister Mark Carney announced retaliatory tariffs on the United States following a breakdown in trade negotiations.

"Canada wants the benefits of being a State, without being one!!!" Mr Trump said in a post on Truth Social.

Since beginning his second term, Mr Trump has made numerous references to making Canada the "51st state" of America, which has infuriated the northern neighbours.

Earlier, Mr Carney said that new Canadian tariffs would take effect on September 8, notably targeting the US steel and dairy industries.

New 50 per cent US tariffs impacting about $US20 billion ($28 billion) worth of goods, or 5.5 per cent of Canadian exports to the US, came into force on Saturday.

The "dollar for dollar" tariffs on imports of US steel, electronics and other products mark a further worsening of relations between the longtime allies and major trading partners.

The two countries failed to reach a trade deal late on Friday, with each side blaming the other for derailing three days of intensive negotiations.

The breakdown complicates the future of a US-Mexico-Canada free-trade pact.

Mr Trump's new tariffs hit sectors including wine, furniture, dairy products, cement, clothing, fishing rods and hockey equipment,

These duties do not exempt Canadian products under the three-nation trade deal, which has shielded most Canadian exports to the US in the past 18 months.

The new US tariffs cover around 5 per cent of Canada's exports to the US.

They could expose some vulnerable industries such as softwood lumber and wine to severe damage and lead to job losses and business closures, trade experts have said.

"We will be mobilising our network of businesses in all regions and all sectors to brace for impact and make the best of a bad situation," said Candace Laing, CEO of the Canadian Chamber of Commerce.

Ontario Premier Doug Ford, one of the most vocal opponents of US tariffs, supported Mr Carney's decision to retaliate.

"I'm glad he didn't sign that deal because it was a bad deal. It was a bad deal for Ontario. It was a bad deal for the auto sector, the steel sector, and the manufacturing sector," Mr Ford said.

There were also US proposals that affected Canadian culture, language and sovereignty, Mr Carney said, without elaborating.

He was elected last year on a promise to be a tough negotiator with Mr Trump, and remains broadly popular. Polls show most Canadians oppose making any concessions to the US.