Danish Prime Minister Mette Frederiksen on Monday warned about the implications of President Donald Trump’s threats to annex Greenland, saying it could be the end of the North Atlantic Treaty Organization (NATO).

Frederiksen told Danish broadcaster TV2 in an interview that Trump’s threats about Greenland should be taken seriously.

"But I also want to make it clear that if the U.S. chooses to attack another NATO country militarily, then everything stops. Including our NATO and thus the security that has been provided since the end of the Second World War," she said, the U.S. needs Greenland, a Danish territory, for "national security."

European and Nordic leaders pushed back against the comments, with Finnish President Alexander Stubb, Norwegian Prime Minister Jonas Gahr Støre and Denmark’s Ambassador to the United States Jesper Møller Sørensen underscoring their support for Denmark’s sovereignty over Greenland and stressing that its future must be determined by Greenland and Denmark alone.

White House deputy chief of staff for policy Stephen Miller doubled down on Trump’s remarks, protect and defend NATO and NATO interests, obviously Greenland should be part of the United States," he added.

Greenlandic Prime Minister Jens-Frederik Nielsen said in a Monday statement posted on Facebook that his country is "not an object of superpower rhetoric."

"We are a people. A land. And democracy. This has to be respected. Especially by close and loyal friends," Nielsen wrote in part.

"Threats, pressure and talk of annexation do not belong anywhere between friends," he added. "That’s not how you talk to a people who have repeatedly shown responsibility, stability and loyalty. This is enough."