Washington DC - President Donald Trump hit back at Canada on Sunday after Prime Minister Mark Carney announced retaliatory tariffs on the US following a breakdown in trade negotiations.

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

"They have also charged our great farmers, for many years, massive amounts of Tariffs. No more!!!" he said.

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

Canada JD Vance mocks insults Carney amid tenuous US-Canada trade negotiations

New 50% US tariffs impacting about $20 billion worth of goods, or 5.5% of Canadian exports to the US, came into force Saturday.

Impacted products range from hockey sticks to cement.

While Trump had initially expressed optimism about a deal, the Canadian leader said Saturday that the US had set conditions that were ultimately unacceptable.

"In recent days, the United States proposed new terms that were uneconomic, unfair, and undermined the net benefits for Canada, and called into question the reliability of any deal. In short, they asked too much, and they offered too little," he said.

Carney further accused the president of launching a full-blown trade "war" and added, "You're at war when you get attacked. We got attacked."