Sri Lanka, March 5 -- Justin Trudeau has claimed the aim of a "dumb" trade war launched by Donald Trump is to usher in the "complete collapse" of the Canadian economy and make it easier for the United States to annex Canada.

Speaking hours after the US slapped 25% taxes on Canadian and Mexican goods - and a 10% levy on Canadian energy exports - the prime minister announced retaliatory tariffs on US exports and said his country would remain defiant against the aggression.

"We've been in tough spots before ... but we have not only survived, we have emerged stronger than ever, because when it comes to defending our great nation, there is no price we all aren't willing to pay, and today is no different," he said.

Trudeau, who will step dow...