"Countries should own their property and protect it, not the things they have rented. And we would have to protect Greenland," said Trump on Friday in response to a question from the BBC to journalists.
He added that Washington could achieve this the "easy way" or the "hard way."
Recently, the White House administration announced that it is exploring several ways to control the autonomous territory belonging to Denmark, a NATO member like the United States. Washington is considering buying the island but does not rule out annexing it by force.
Denmark and Greenland claim that this territory is not for sale. Copenhagen emphasizes that a US military operation against Denmark would mean the end of the North Atlantic defense alliance.
On Friday evening, Greenland's main parties, including opposition leaders, issued a joint statement calling to "stop the US hatred towards our country."
"We do not want to be American, we do not want to be Danish, we want to be Greenlandic," the statement says. "The future of Greenland must be determined by Greenlanders themselves."
