Speaking to reporters at an event where he also addressed looming sanctions on Iran and a pause on higher tariffs on ground beef, Trump signed the order changing the name of the body of water that forms part of the U.S.-Canada border.
"We're going to be changing the name of Lake Ontario effective immediately to Lake America," Trump told reporters before signing the order, according to The Hill.
The president first floated the idea earlier this year as tensions with Canada escalated. The renaming is seen by critics as another escalation in the trade war, which has already led to retaliatory tariffs on both sides. The BBC reported that trade talks between the U.S. and Canada broke down late last week.
The order changes the name of one of the Great Lakes, a stretch of water that has been known as Lake Ontario since European colonization and is shared by the U.S. state of New York and the Canadian province of Ontario.
Canadian officials have not yet issued a formal response to the renaming, but the gesture is expected to further strain relations between the neighboring nations.