Denmark has summoned the top U.S. diplomat after the national broadcaster reported that at least three people with connections to President Donald Trump have been carrying out covert influence operations in Greenland

Denmark’s foreign minister has called in the senior U.S. diplomat in Copenhagen following intelligence reports suggesting that American citizens have carried out covert influence activities in Greenland, the ministry confirmed Wednesday.

According to Danish broadcaster DR, citing unnamed sources, officials believe at least three U.S. nationals linked to President Donald Trump’s administration were involved in efforts to encourage Greenland’s secession from Denmark and closer alignment with the United States.

“We are aware that foreign actors continue to show an interest in Greenland and its place within the Kingdom of Denmark,” Foreign Minister Lars Lokke Rasmussen said in a statement. “It is therefore not surprising if we see attempts from outside to influence the future of the Kingdom going forward.”

The ministry did not identify any individuals, nor did DR. The U.S. embassy in Copenhagen has not yet commented.

The U.S. mission is currently led by chargé d’affaires Mark Stroh, while Trump has nominated PayPal co-founder Ken Howery as ambassador to Denmark, pending Senate confirmation.

Greenland, an autonomous territory of Denmark, has strategic importance due to its mineral resources and location in the Arctic. Trump has openly said he would like the United States to acquire Greenland for reasons of national security, a proposal firmly rejected in both Copenhagen and Nuuk. While he has since said he respects Greenland’s right to decide its own future, his remarks about potentially taking the island by force have unsettled many of its roughly 57,000 residents.