Danish Prime Minister Mette Frederiksen told The Associated Press “you cannot spy against an ally” after reports that the United States has stepped up intelligence gathering on Greenland, a semi-autonomous Danish territory coveted by U.S. President Donald Trump.

Frederiksen's comments Friday are the latest in the spat between Denmark, Greenland and the United States because Trump seeks to annex the strategic Arctic island. Denmark and Greenland insist that the mineral-rich island is not for sale, while Trump has not ruled out taking it by military force even though Denmark is a NATO ally.

The Danish prime minister spoke to the AP the day after Denmark summoned the top American diplomat in the country for an explanation following a Wall Street Journal report which said several high-ranking officials under the U.S. director of national intelligence, Tulsi Gabbard, had directed intelligence agency heads to learn more about Greenland’s independence movement and sentiment about U.S. resource extraction there.

Jennifer Hall Godfrey, acting head of the U.S. Embassy in Copenhagen, met with high-ranking Danish diplomat Jeppe Tranholm-Mikkelsen at the Danish Foreign Ministry, the ministry said in an email. It provided no further details. The embassy declined to comment.

Frederiksen said Friday the report was “rumors” in an international newspaper. The Journal, cited two people familiar with the U.S. effort which it did not identify.

“Cooperation about defense and deterrence and security in the northern part of Europe is getting more and more important,” Frederiksen said. “Of course, you cannot spy against an ally.”

Greenlandic Prime Minister Jens-Frederik Nielsen, in comments to Greenland newspaper Sermitsiaq, said the reports of espionage are unacceptable and disrespectful.

In response to questions about the Journal’s report, Gabbard’s office released a statement noting that she had made three “criminal” referrals to the Justice Department over intelligence community leaks.

“The Wall Street Journal should be ashamed of aiding deep state actors who seek to undermine the President by politicizing and leaking classified information,” Gabbard wrote. “They are breaking the law and undermining our nation’s security and democracy. Those who leak classified information will be found and held accountable to the fullest extent of the law.”

Greenland’s prime minister said last month that U.S. statements about the island have been disrespectful and it “will never, ever be a piece of property that can be bought by just anyone.”

Norwegian Prime Minister Jonas Gahr Store on Friday said those who believe there is “another kind of legal regime in the Arctic” should be told that “this is not the case.”

Speaking ahead of a Joint Expeditionary Force leaders’ meeting in Oslo, Gahr Store said there seemed to be suggestions that “in the Arctic, there is some kind of terra nullius, law doesn’t apply.”

“It applies, sovereignty applies. And Greenland is a part of the Kingdom of Denmark,” he said ahead of the meeting with the leaders of the U.K., Nordic and Baltic nations.

Danish leader says 'you cannot spy against an ally' after reports of US gathering Greenland info