US President Donald Trump on Thursday ordered Lake Ontario to be renamed "Lake America" as he escalated his trade war with Canada, sparking immediate pushback from Ottawa.

Trump stepped up his trolling of Canada by signing an executive order changing the name of the body of water on the border between the North American neighbours.

However, Canadian Prime Minister Mark Carney swiftly rejected Trump's move, saying it would be called Lake Ontario "then, now and always."

The US leader's move comes after US-Canada trade talks collapsed at the last minute last week, prompting the two longtime allies to slap tit-for-tat tariffs on each other.

"We're going to be changing the name of Lake Ontario effective immediately to Lake America," the 80-year-old Republican told journalists as he signed the order at the White House.

Asked why he was targeting an ally for punishment instead of America's adversaries, Trump replied: "The Canadian officials have treated us very badly. They're nasty people."

Lake Ontario is the smallest by surface area of the five Great Lakes, which straddle the border between the United States and Canada. It borders the Canadian province of Ontario and the US state of New York.

The name change mirrors Trump's unilateral altering of the name of the Gulf of Mexico to the Gulf of America in January 2025 – a move Mexico has also rejected.

Carney retorted that the name of the lake was 400 years old – predating the formation of both the United States and Canada – and came from an Indigenous word meaning "the lake is beautiful, the lake is big".

"We know that America is changing," he said in a post on X. "Canadians also know that naming reality means calling it Lake Ontario – then, now and always."

In Toronto, Canada's largest city which lies on the lake's northwestern shore, Canadians and Americans alike criticised Trump's move.

"Typical Trump. He's being a bully, he goads, he antagonises," said Mark Weicker, who lives in Kitchener, west of Toronto.

Megan Smith, who hails from New Jersey, put it bluntly: "It just makes him look stupid." (AFP)


Edited by Aaron Tam