US President Donald Trump on Thursday ordered Lake Ontario to be referred to as “Lake America” in the United States, escalating his ongoing trade dispute with Canada.

Trump signed an executive order in the Oval Office directing the US geographic naming authority to update the lake’s name.

The order applies to the US naming system, but Trump has no authority to require Canada to adopt the new name, as Lake Ontario is shared by the two countries.

The move echoes Trump’s decision last year to rename the Gulf of Mexico as the “Gulf of America” for US government use.

Lake Ontario is one of the five Great Lakes of North America and lies along the US-Canada border.