Canadian Prime Minister Mark Carney pushed back sharply on Thursday after President Donald Trump signed an executive order renaming Lake Ontario as “Lake America,” responding with a pointed reminder of the lake’s deep historical roots.

Within hours of Trump’s order, Carney rejected the change outright, citing the name’s Indigenous origins and more than 400 years of history before insisting Canadians would continue to call it Lake Ontario “then, now and always.”

“The name Lake Ontario comes from the Wendat word Ontari’io, which, appropriately, means ‘the lake is beautiful, the lake is big,’” Carney wrote on X.

“The name is more than 400 years old, predating both the Confederation of Canada and the Declaration of Independence of the United States of America.”

The prime minister then appeared to take aim at the sweeping shifts unfolding in the United States under Trump’s leadership.

“We know that America is changing. Their trading relationships, their foreign policies, their national monuments, their hydronyms,” he wrote.

“Canadians also know that naming reality means calling it Lake Ontario – then, now and always.”

Carney’s response followed Trump’s Oval Office signing from behind the Resolute Desk, where the president directed the Interior Department to use “Lake America” as the lake’s official name for US federal purposes.

The president cannot compel Canada or international organizations to adopt the new name but Trump’s action triggered fury from liberals and delight among MAGA supporters.

Trump put pen to paper in the Oval Office on Thursday, declaring the name change effective immediately as his increasingly bitter trade war with America’s northern neighbor spilled onto the map.

The move instantly became another political flashpoint, with Trump supporters hailing it as masterful trolling while critics branded the president a ‘child,’ a ‘moron’, accusing him of turning the United States into a ‘national embarrassment.’

Trump appeared to relish the controversy as he signed the order.

‘I guess the purpose of this, more than anything else, is we’re going to be changing the name of Lake Ontario, effective immediately to Lake America,’ he said. ‘That’s going to take place right now as I sign the order.’

The president said he had contemplated the change for a ‘long time’ and suggested he may not be finished tinkering with the map – joking that the Atlantic or Pacific Ocean could eventually find itself in his sights.

‘Actually, as you know, we took something called the Gulf of Mexico and we changed it, and now it’s very routinely the Gulf of America,’ Trump said.

‘So, if you think about it, we have a Gulf and we have a lake. Now, all we need is an ocean. So, maybe we’ll have to change the name of the Atlantic and/or the Pacific.’

The order directs Interior Secretary Doug Burgum and his department to update the federal Geographic Names Information System to reflect the new US designation.

‘We’re on it, Mr. President!’ Burgum wrote on X. ‘The places and waters that border our nation and support our economy should reflect the greatness of the United States.’

Lake Ontario forms part of the international boundary between New York and the Canadian province of Ontario and has been jointly managed under the 1909 Boundary Waters Treaty for more than a century.

Trump nevertheless emphasized the large portion of the lake bordering the United States as he championed his new name.

His supporters quickly embraced the move.

‘THE LAKE AMERICA TROLL JUST BECAME AN EXECUTIVE ORDER,’ conservative commentator Glenn Beck wrote after previously describing the idea as ‘top tier’ trolling.

But the reaction from Trump’s opponents was blistering.

‘This is why we can’t have nice things,’ Democratic California Rep. Ted Lieu wrote on X.

Senator Bernie Sanders dismissed the rebranding and urged Trump to concentrate instead on issues affecting Americans at home.

‘No, President Trump. The American people don’t want to rename Lake Ontario Lake America,’ Sanders wrote, before calling on the administration to focus on healthcare and other domestic priorities.

Journalist John Harwood was even more scathing, describing those behind the move as ‘Pitiful morons.’

Bulwark editor Sonny Bunch wrote: ‘Anyone who unironically calls Lake Ontario “Lake America” should be ruthlessly mocked. Dumbest sh*t imaginable.’

The announcement comes at a particularly explosive moment in US-Canadian relations.

Trade negotiations between the longtime allies have collapsed, with Trump threatening punishing new tariffs on Canadian goods and Carney promising Canada will retaliate ‘dollar for dollar.’

Trump has said tariffs on Canadian cars, trucks, automotive parts and steel will rise to 50 percent by 2027 as he attempts to force more manufacturing into the United States.

And while signing Thursday’s order, the president made clear that his dispute with Ottawa was far bigger than the name of a lake.

‘The whole Canadian thing … has to come to a stop,’ Trump said. ‘We are going to be doing tariffs on their cars that are coming in at a substantial level because we want to make the cars here.

‘They can make their own cars if they want and they can continue to make cars for Canada but we don’t want them to make cars for the United States of America. It’s very simple. Likewise many other products.’

Trump also accused Canada of relying on the United States for military protection without adequately compensating Washington.

‘We defend Canada for nothing, we don’t get anything,’ he said. ‘We love the people of Canada, but their representatives aren’t doing an appropriate job.’

The president has separately branded Canadian officials ‘nasty people’ and described the country as one of America’s most difficult trading partners.

‘People oftentimes they’ll ask me who’s the worst to deal with on trade, and I said that’s easy, Canada,’ Trump said.

‘They are the worst to trade, and they feel entitled, and just we can’t have that.’

Carney, meanwhile, has been increasingly combative toward Washington as the dispute escalates.