Ontario Premier Doug Ford has installed a large sign saying, ‘Lake Ontario. Now and forever’ along the shoreline of the lake in response to U.S. President Donald Trump’s renaming of the body of water as Lake America.

The billboard was written in English and French and unveiled near the U.S.-Canada border.

“Long before President Trump, this lake was called Lake Ontario. Long after President Trump is gone, it will still be called Lake Ontario,” Mr Ford told reporters on Sunday. “Just in case President Trump or anyone else forgets, we’ve set up this sign to remind them it’s Lake Ontario, now and forever.”

Mr Trump signed an executive order on Thursday directing the renaming of Lake Ontario as Lake America.

Lake Ontario is the smallest of the five North American Great Lakes by surface area and borders Ontario and New York.

The order said the name 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 does not require Canada or other countries to adopt it.

Mr Trump has since shared AI-generated videos on social media showing the lake as Lake America, including one depicting a Lake Ontario sign replaced with one that reads, ‘Welcome to Lake America’.

Google said on Saturday that it had updated maps, noting, “Since we update Google Maps to reflect name changes in official government sources, which is GNIS for the U.S., people using Maps in the U.S. will see ‘Lake America’. Those in Canada will continue to see ‘Lake Ontario’, and those outside of the U.S. and Canada will see both names.”

“President Trump can call it whatever he wants, but I can tell you the rest of the world will always call it Lake Ontario,” Mr Ford said. “We’re resilient, and we’re strong Canadians who are always going to protect our sovereignty, always, and we’ll never ever back down from a bully, ever.”

The disputes come amid an escalating trade war between the neighbouring countries.

The Canadian government announced last 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.

Canadian Prime Minister Mark Carney responded to Mr Trump’s executive order, saying, “Things must be called by their name, and this lake is called Lake Ontario—today and forever.”