Denmark Prime Minister Mette Frederiksen said "you cannot spy against an ally" after reports that the U.S. was gathering intelligence on Greenland.

Denmark summoned the top U.S. diplomat in the country for an explanation following a Wall Street Journal report about the United States stepping up its intelligence gathering on Greenland, a semi-autonomous Danish territory coveted by President Donald Trump.

Officials summoned the American ambassador to express its displeasure after the Trump Administration was said be ratcheting up surveillance.