Denmark, Norway, Sweden, France, Germany, the United Kingdom, the Netherlands and Finland would face the tariff.
Trump's comments came hours before Vice President JD Vance was to host Danish and Greenlandic officials for talks.
Deposed Venezuelan leader Nicolás Maduro declared himself “innocent” as he pleaded not guilty. His next court date is March 17.
President-Elect Trump has also floated having Canada join the United States.
The president-elect is renewing unsuccessful calls he made during his first term for the U.S. to buy Greenland from Denmark.
Danish Prime Minister Mette Frederiksen says she is "disappointed and surprised" by President Trump's decision to cancel his visit to Denmark after she rejected suggestions of selling Greenland to the U.S.
President Donald Trump says the idea of buying Greenland from Denmark came up in conversations within his administration and that it's essentially "a large real estate deal."
Aiming to put his mark on the world map, President Donald Trump has talked to aides and allies about buying Greenland for the U.S.
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