DENMARK summoned the top US diplomat in the country today to explain reports that Washington is carrying out covert “influence operations” to undermine its sovereignty in Greenland.

European states routinely accuse Russia of running such operations to affect public opinion and elections in their countries, usually without hard evidence, but for Nato member Denmark to accuse the United States of doing so underlines the tensions placed on the alliance by the Donald Trump presidency.

Mr Trump has repeatedly threatened to annex Greenland, suggesting the US could buy the huge Arctic island from Denmark — as it bought Alaska from Russia in the 19th century — but also stating that he does not rule out military conquest. An attack on Danish territory by the US would place Nato in a quandary, since it would technically trigger its Article 5 provision obliging members to come to Denmark’s aid, but the alliance’s military structure subordinates member states’ armies to the US, with the commander of its Allied Command Operations always being a four-star US general, currently General Alexus Grynkewich.

Danish broadcaster DR reported today that at least three US citizens with connections to Mr Trump have been working to build US influence, with two cultivating political and business leaders and one collecting lists of names of Greenlanders who were either friendly or hostile to US annexation.

Danish Foreign Minister Lars Lokke Rasmussen said: “We are aware that foreign actors continue to show an interest in Greenland and its position in the Kingdom of Denmark.

“Any attempt to interfere in the internal affairs of the kingdom will of course be unacceptable.”

Mr Trump has said acquiring Greenland is essential for US security. There is growing interest in mineral and energy resources becoming more accessible due to the melting polar ice caps, and the island holds some of the world’s largest reserves of rare earths. 

The Trump administration regards China’s domination of global rare earth mining and processing as a supply chain risk, declaring in March that “our national and economic security are now acutely threatened by our reliance upon hostile foreign powers’ mineral production,” and has increased subsidies to US firms in the sector.