President Donald Trump signed an executive order on Thursday renaming Lake Ontario to "Lake America." 

The order directs Interior Secretary Doug Burgum to work with the Board on Geographic Names to reflect the new name. It explains that the U.S. claims most of the lake's volume, and its deepest parts lie within the U.S. 

During the signing in the Oval Office, Trump said the change in name is "effective immediately." However, the order gives Burgum 30 days from the date of the order to "take all appropriate actions to rename as 'Lake America' the body of water currently named as Lake Ontario." 

Trump had announced on Monday his intention to do so amid tensions with Canada over tariffs.