India, Feb. 2 -- Hours after US President Donald Trump signed an executive order imposing 25 per cent tariffs on almost everything the US imports from Canada, outgoing Canadian Prime Minister Justin Trudeau said he has no choice but to impose countermeasures.

In a press conference in Ottawa, Justin Trudeau addressed Americans directly and invoked the two neighbouring countries' shared history and longstanding security and military alliances.

"From the beaches of Normandy to the mountains of the Korean peninsula, from the fields of Flanders to the streets of Kandahar, we have fought and died alongside you during your darkest hours," Trudeau said.

"Yes, we've had our differences in the past, but we've always found a way to get past them....