The tariffs took effect after a deadline set by US President Donald Trump expired at 12:01am Eastern Time (04:01 GMT) on Saturday, with officials from both countries confirming that no agreement had been reached.

In response, Canadian Prime Minister Mark Carney said Ottawa would match the new tariffs “dollar for dollar”.

“In recent weeks, we made important progress toward improving Canada’s position as having the best deal in the world with the US,” said Carney in a statement.

“However, that progress has not been enough to meet our objectives for Canadians.”

Carney also said his government would introduce new measures in the coming days to support workers and businesses and protect Canadians from the impact of the trade war.

Meanwhile, US Trade Representative Jamieson Greer blamed Canada for the failure to reach an agreement.

“It was “a missed opportunity for Canada to partner with the United States”,” Greer said.

“Canada declined to finalise the trade deal under the terms agreed earlier this week,” Greer said.

“Despite the US offer to Canada to receive the best treatment of any major exporter to our market, new demands and walkbacks of other commitments by Canada have upended the careful balance reached in the past days.”

The new tariffs will affect about 5 percent of Canadian exports to the United States, including electronics, industrial machinery and dairy products.

The measures add to existing US tariffs on Canadian steel, lumber and automobiles.

Earlier, Trump imposed tariffs on key imports from Canada at the beginning of his second term last year, prompting Ottawa to respond with a series of countermeasures.

Since then, the two countries have repeatedly exchanged tariff measures and threats, with Trump periodically announcing new plans to impose additional duties.

The Trump administration announced the latest tariffs in July after Trump accused Canada of “discriminatory treatment of American products”.

However, Trump told reporters on Friday that he expected a deal with Canada could be reached, a prospect that did not materialize before the deadline.

The tariffs could put additional pressure on Canadian businesses that export affected products to the US.

“Tariffs of 50 percent would effectively price hundreds of Canadian goods out of the US market,” Julian Karaguesian, a lecturer and trade expert at McGill University in Montreal, told Al Jazeera earlier this week.