Washington/Ottawa, Aug. 22 -- The US-Canada trade war flared anew on Saturday after last-minute negotiations collapsed, setting in motion a new 50 per cent US tariff on roughly $28 billion worth of Canadian goods and prompting Prime Minister Mark Carney to vow dollar-for-dollar retaliation.

Carney said Canada had suspended trade negotiations with Washington after last-minute changes to proposed US terms were deemed "unfair" and "uneconomic," ending hopes of a deal just hours before the midnight deadline.

"At midnight tonight, the US intends to impose a 50 percent tariff on roughly $28 billion of Canadian goods. Canada will match those tariffs dollar for dollar to protect our workers and businesses," Carney said in a statement.

He said th...