U.S. President Donald Trump said on Thursday that the United States could rename the Atlantic and Pacific oceans as the “American Ocean” amid the escalating trade war with Canada.

“We have a Gulf, and we have a lake—now all we need is an ocean,” Mr Trump told reporters at the Oval Office. “Maybe we’ll have to change the name of the Atlantic and/or the Pacific.”

He added, “Maybe we’ll change them both.”

Mr Trump made the remarks during the signing of an executive order renaming Lake Ontario—the smallest of the five North American Great Lakes by surface area and named after a Canadian province—‘Lake America’.

He said the change would take effect immediately and directed federal agencies to update the name on U.S. maps, documents and databases.

However, because the body of water borders the U.S. and Canada, the name change may not be effective in Canada.

The president described the neighbouring country as the “worst” trade partner, adding that “They feel entitled, and we can’t have that.”

He also signed an executive order last year renaming the Gulf of Mexico the Gulf of America. The Mexican government rejected the move.

The premier of Nova Scotia, Tim Houston, responded to the move on social media, saying, “We’re into some real foolishness now. It’s Lake Ontario, buddy.”

The U.S. president’s latest remarks came after the Canadian government said on Tuesday that it would impose tariffs ranging from 15 per cent to 50 per cent on 700 U.S. products from September 8 in response to the Trump administration’s measures against Canadian goods.

Since returning to the White House last year, Mr Trump has slapped Canada with tariffs on key imports, and the neighbouring country has retaliated. The two countries have since engaged in a cyclical trade dispute, with Mr Trump repeatedly threatening new measures.

The U.S. remains Canada’s largest trading partner, while Ottawa is Washington’s second-largest trading partner after Mexico. However, the dispute escalated last week after trade negotiations between the two countries failed.